It is no secret that Heidelberg is a jewel among German travel destinations. Heidelberg is located in the Neckar river valley right where the legend-rich Odenwald (Forest of Odes or Odin) opens up towards the plains of the Rhine Valley. Heidelberg is home to the oldest university in Germany (est. 1386). With 28,000 students, the Ruprecht-Karls-Universität (or Ruperto Carola, the Latin equivalent of its name) is one of Germany's larger academic institutions and boasts the full spectrum of an ancient academy, from Egyptian Studies to Computer Linguistics. The faculties for Medicine, Law and Natural Sciences are considered to be among the best in Germany. The university fostered the establishment of several other world class research institutions such as the German Cancer Research Center (DKFZ), the European Molecular Biological Laboratory (EMBL), Center for Molecular Biology (ZMBH), Max Planck Institutes for Medicine, Astronomy, Nuclear Physics, among others. Generally speaking, Heidelberg is an academic city with a long and rich history and is similar in many ways to cities such as Cambridge or Oxford (Heidelberg and Cambridge, England are twinned).
During WWII, the city was almost completely spared allied bombings which destroyed many of Germany's larger inner cities. As a result, Heidelberg has retained its baroque charm of narrow streets, picturesque houses and of course the world-famous Schloss (castle ruins). After World War II, the US Army built large barracks at the southern end of the city. Heidelberg's 147,000 inhabitants thus include not only 28,000 students at the university but also nearly 30,000 US citizens, almost all of them soldiers and their families. With hundreds of thousands of tourists flocking to the city annually, Heidelberg is truly a culturally diverse and international destination, despite its small size.
Over the years, Heidelberg has attracted numerous artists, intellectuals and academics from all over Europe and has sometimes been referred to as Germany's unofficial intellectual capital. People who have lived and worked in the city include the poets Joseph von Eichendorff, Jean Paul, Goethe and Iqbal, scientists such as Bunsen and Kirchhoff, philosophers such as the founder of the "Illuminati" order von-Knigge, atheist Ludwig Feuerbach, existentialist Karl Jaspers, political theorist Hannah Arendt, architect Albert Speer, and many more. Mark Twain wrote in A Tramp Abroad:
...Out of a billowy upheaval of vivid green foliage ...rises the huge ruin of Heidelberg Castle, with empty window arches, ivy-mailed battlements, moldering towers—the Lear of inanimate nature—deserted, discrowned, beaten by the storms, but royal still, and beautiful.
Stuttgart - nice for European 'EU-domestic' flights.
ICE Train from Frankfurt or Stuttgart Airport to Heidelberg
You can travel to Heidelberg via ICE (Inter City Express), Germany's fastest train, running at 300 km/h (180 mph) .
Both Frankfurt and Stuttgart airports have train stations inside the terminal. Frankfurt Airport even is a major ICE-train stop.
Reservations are not necessary; just buy your ticket at the counter or machine after you land. Credit cards are accepted; most staff speak English. It might be necessary to change trains (only once) at Mannheim, Stuttgart, or Frankfurt Central Station, but it is still likely to be faster than the bus. One way prices: Frankfurt €24.50 (ICE), Stuttgart €26 (IC) €38 (ICE).
If you don't like trains, but prefer to see the German Autobahn, Lufthansa provides a shuttle bus from Frankfurt to Heidelberg for €23 one way and €40 round trip. If you have a Lufthansa Ticket, you get €2 discount.
Frankfurt-Hahn - An airport in the middle of the beautiful green mountains of Hunsrück is a major hub for Ryanair. There are frequent bus connections from Heidelberg Hbf to Frankfurt-Hahn; the trip takes a little more than 2 hours, and costs €20 (as of 2010).
The main train station Heidelberg Hbf is located in the western part of the city, from there you can take a tram to any place downtown e.g. Bismarckplatz (taxis are not recommended as they are far more expensive than trams!) Check for connections to "Heidelberg Bismarckplatz" on German Railway Website 
For most long distance destinations it is useful to take the regional train to nearby Mannheim Hbf (S-Bahn, about 15 minutes), from where there are frequent direct high speed connections to all major cities in Germany and some places in the nearby countries (e.g. Paris, Zurich, Amsterdam).
The city runs a small rather effective system of trams and buses. The two most important nodal points are the main station and Bismarckplatz. Bus #32 and #33 connect the main train station (Hauptbahnhof) with the old city area; detailed maps, schedules and routes can be found online. A mountain railway runs between four stations (including the castle), linking the old city on the level of the river with the summit of the Königstuhl Mountain, about 400 m (1312 feet) above the city.
The "Heidelberg Card," a tourist pass that includes public transportation, many museums, and the lower section of the mountain railway (a separate fare is required for the upper section), can be bought at the tourist information center located just outside the main station.
The Altstadt (historical city center) and Hauptstrasse (main street). The Hauptstrasse leads from Bismarckplatz across the old town. Approximately one mile in length, it is reputedly the longest pedestrian shopping street in Germany.
The Castle: an audio guide tour of the castle and its grounds is available for a fee near the entrance. It is available in several languages, including English. There is also a statue to the German poet Johann Wolfgang von Goethe in the castle gardens. Currently covered with unsightly scaffolding [Sept 2012] but this is very normal.
The Philosophenweg which can be found on the northern side of the city. It provides a wonderful view across the oldest part of the city. Here you can find the site of the famous Merian Stich (engraving) which is a popular illustration of Heidelberg.
The Heiligenberg mountain which boasts a wonderful view over the old town.
The Thingstätte on top of Heiligenberg (an open-air theatre built by the Nazi regime in 1934 to host propaganda events)
Also on the Heiligenberg the remnants of a wall ancient Celts built to keep Germanic tribes out, the Heidenloch, a deep well with unknown origins, and the ruins of a 10th century cloister.
The Kurpfälzisches Museum on the Hauptstrasse contains interesting exhibits of items from Heidelberg's pre-history to modern times.
The old university on Universitätsplatz in the old city and the adjacent old armory which is now a student cafeteria (but also open to the public).
Jesuitenkirche has 1712 Baroque construction with modern touches inside.
The Heiliggeistkirche church is only one of many large and small churches, but definitely the one with the most interesting history. During the dark ages, it was the shelter of the Bibliotheka Palatina, Germany's oldest library. The Bibliotheka was stolen and brought to Rome but eventually returned in pieces. Today, parts of it can be visited in the University Library (also the oldest and probably the most valuable of its kind in Germany), which is situated close to the old university.
View of cathedral from Heidelberg Castle
You can get a great view of the Heiliggeistkirche, Old Town, and the Neckar river bridge from the castle (Schloss Heidelberg).
The city boasts more than eight theaters, including
Stadttheater the large state-run theater, and
Zimmertheater on Hauptstrasse, Germany's oldest private theater
There are also many progressive culture centers, including the famous Karlstorbahnhof in the east-end of the old city.
Königstuhl-Mountain, 568 m (1560 ft) high, 450 m (1480 ft) above Heidelberg, is a nice option to escape the hustle and bustle of Heidelberg downtown. The mountain top of Königstuhl offers a nice view over Heidelberg and the Rhine Valley. In good weather conditions you can see the Northern Black Forest. The same funicular railway that carries visitors to the castle continues to the mountain top. You will have to change trains once -- the final one to the top is a historical wooden funicular train. (A separate fare is required for the historical funicular.) On the top you can have a look at the more-than-100-year-old engine that just pulled you up. (No worries -- made in Germany!)
If you feel more energetic, you can take the Himmelsleiter (Heaven's Ladder or Sky Ladder) -- a stairway of 1200 steps winding up 270 meters (890 ft) up to Königstuhl. It ends 10 meters east of the mountain top funicular station. The lower end of stairs is just above the castle, but a bit hidden - ask locals or look it up on this map.
BBQ & Beer - On sunny summer days the "Neckarwiese" ('Neckar meadow', northern bank of Neckar river, just west of Bismarckplatz) is full of people relaxing in the sun, having a Barbecue or a beer... This place also offers a nice view to the castle. You will have to bring your own grill, beer and steaks. Cheap grills to use once are availible at the "Bauhaus" do-it-youself store at Kurfürsten-Anlage 11, just 200m south of Bismarckplatz. Nice way to mix with locals.
Snacks: Along the Hauptstrasse, which runs through the center of town, you will find several bakeries that serve local specialities including “Brezeln” (pretzels). Department stores have a nice selection of delicatessen stalls called “Markthallen” where you can eat everything on the spot.
Many of the cafes in Heidelberg set up outside tables when the weather is fair, and these are enjoyed by locals and tourists alike. A popular destination for summer cafe beer sipping and lounging is the Marktplatz, which is adjacent to the Heiliggeistkirche.
Meals: The Haupstrasse is plentiful with an amazing variety of restaurants. Dishes tend to be served in large portions, relatively inexpensive and of good quality. You can find something for almost every taste including Japanese, Indian, Italian, Chinese, German and Bavarian. American fast food and "Döner" restaurants cater to the budget conscious and late-night crowds.
Mensa im Marstallhof Maybe the most beautiful University Canteen in Germany, offering food and beer at low prices in a historic buildling and a Beer Garden!. Everybody is welcome, Open till late...
Sunisas Thai Imbiss, Speyerer Straße 1, 69115 Heidelberg,  6221 / 6555533: if you want a change from German food: an authentic, tasty Thai diner and takeaway with reasonable prices. It also has terrace, pool tables and cocktails. Open at 11am till late at night.
Supan's Thai Bistro, on the Hauptstraße right at the Universitätsplatz next to the "Vinyl Only" record shop. An excellent, reasonably priced, Thai restaurant, with great service. The food is as authentic as it can get in Europe. Ask for "Thai spicy" if you want the real thing but only if you can deal with it!
Korean/Sushi restaurant, Heiliggeiststraße 3, close to the Marktplatz, next to the Hotel zum Rathaus, a seemingly little-known, but great sushi place (also serves Korean food).
BrunnenStube (Restaurant BrunnenStube), Kranichweg 15 (see website for directions), ☎  6221 734222, . Mon.-Sat. from 17:00, closed Sundays and some public holidays;. Nice restaurant with modern german cuisine and moderate prices. Great fish, lamb and many seasonal specials. Located in the west of Heidelberg's center in a living area. Patio dining in summer.Main course from 7.90 EUR to 18.90 EUR. edit
More than 300 bars, pubs, clubs, discotheques and the like, from Bavarian style tourist restaurants with deer antlers on the walls to extremely left-wing student bars which reserve the right to refuse police officers entry to the bar. You name it. Find your place and enjoy yourself. Heidelberg knows no curfew. Most bars close at 1am, but especially the students bars are often open until the early morning. Although the locals -- even the police officers -- are used to drunk tourists as well as to drunk students, please be calm on your way home and do not riot. As a remnant of the student revolts, Heidelberg has the largest ratio of policemen per capita and you may find yourself in the arms of an officer much faster than you think.
If you are a young person and happen to discover one of the student parties (which are quite numerous but advertised mostly by word-of-mouth), you scored the jackpot. Get inside, get a (dirt cheap) beer and have fun. But try and avoid being recognised as a tourist. No party ends before 3am and many run until 6 or 7am. Either Untere Straße or the Zieglers (Heidelbergs oldest students' bar) are frequently crowded with students.
Wines are produced around Heidelberg (e.g. Schriesheim, Wiesloch), but it might be difficult to get hold of them - unless you simply go to a vineyard... When you buy wine, always a safe bet is a Riesling from Pfalz or some white wine from Baden instead, or try any of the numerous wines from other German wine regions.
Vineyards Vineyards are usually located in the middle of small towns along Bergstraße (Highway B3). Fruit farmers sell wine right on their farm e.i. vineyard - make sure you also ask for Apple Wine (Hesse specialty) and New Wine (wine still in process of fermentation - sold from the barrel, bring a canister!) which you can sometimes drink in some 'wine-beergarden' right on site. Take a tram (5/5R) northbound to any place between Schriesheim and Lützelsachsen or a local train (S3/S4) southbound to Wiesloch - or (even better, if you have the time) S1 or S2 to Neustadt, where you will find yourself in an endless landscape of vine stocks.
Next to the Old Bridge, there are two small breweries: The Kulturbrauerei in the Leyergasse and Vetter's Brauhaus in the Steingasse. Vetter's is famous for having one of the strongest beers in world (Vetter 33).
Mensa im Marstallhof Maybe the most beautiful University Canteen in Germany and maybe also Heidelberg's cheapest Beer Garden. Serving Welde-Beer (the Beer with screwed bottle necks and answering on any question... ) Everybody is welcome, Open till late...
If you want to mix with the locals, try the Untere Strasse, which runs between the Hauptstrasse and the river, parallel to both. It is packed with the student bars, including the crowded:
Großer Mohr. Small but highly recommended. Tuesday night the odds are high to find the Mohr besieged by medical students. Thursdays are also Ladies Night, where girls receive free Sekt, making it a popular destination leading up to the weekend.
Sonderbar. The latter boasts a huge collection of absinthe, whiskeys and whiskys, as well as a very distinctive atmosphere.
Destille. There is a tree in in the center of the establishment.
O'Reillys, . An Irish pub north of the river, just over the bridge from Bisi (Bismarckplatz).
Dubliner A good Irish pub at the center of Heidelberg Mainstreet (Downtown)
Ham Ham's A great place to chill, drink, and smoke.
Nektar A very relaxed and chill place to enjoy a drink and party
B.J.Z. Bar Great place to party in Emmertsgrund, its a B.Y.O.A. (Bring your own alcohol) and you can crash anywhere in the house
The Brass Monkey Friendly bar on Haspelgasse, just opposite the old bridge. Good crowd and all staff also speak fluent English.
If you are looking for coffee rather than alcohol, Star Coffee has two branches, one off Bismarckplatz and the other on the Hauptstrasse, serving a variety of coffees and offering free WiFi access. Fewer computers but more style are found in the two Moro Cafes, directly at the Alte Brücke and one on the Hauptstraße.
Recently, most pubs close much earlier in the night, even on the weekends at around 2am. Just move to one of the numerous clubs, which usually have no entrance fee this late at night.
Heidelberg is an extremely safe city (even by German standards). However, women walking alone at night should take the usual precautions they would do anywhere else. Walking along the northern Neckar banks at night would not be advised, except in groups, particularly by the Studentenwohnheime (dorms). The shrubs are thick and it is very dark.
Usually there won't be any problem. If you are a bit 'paranoid' you can take a Taxi. If you are from New York, you might think they are cheap - if you are from East-Europe or Asia you will feel like they are ripping you off... use as needed. There are also "Frauentickets" available for women, you can buy these coupons for 8€ and they will cover the fare for anywhere in the city.
Don't walk on bicycle lanes! - Really don't! (they are often painted in red, but always separated from the pedestrian lanes by a white line): Heidelberg has more cyclists than motorists, and many of them have a rather cavalier way of riding. The southern parallel street to Hauptstrasse (called Plöck) is the main traffic channel for student cyclists between Bismarkplatz and University Square. During the day it can be such a buzz, it's already a sight worth visiting. But watch out: Many cyclists feel safe from the tourists there and lose all their good manners.
Steffi's Hostel Heidelberg, Alte Eppelheimer Str. 50 (Just walk straight out of the station and cross the big street and the tram rails in front of you. On the other side there's a modern building, where you enter a shopping arcade (Kurfürstenpassage – Jack Wolfskin / Backpacker Store). Again you walk straight ahead through the passage and leave it on the opposite side. From the exit you can already see a big brick stone building in front of you. Here on the third floor above the Lidl supermarket, Steffis Hostel Heidelberg is situated.), ☎ +49 (0)6221/7782772 (email@example.com), . checkin: 10am - 1pm and 5pm - 8pm; checkout: until 12. Dorms from 20 Euro, everything included. edit
Youth Hostel Heidelberg, Tiergartenstrasse 5, ☎ 06221/65119-0, . (Jugendherberge Heildelberg) Large well maintained hostel, located on the eastern bank of the Neckar River, 25 min walk away from the central rail station. Public transportation: take bus 32 from central rail station towards north (Sportzentrum Nord), get off at Jugendherberge stop. Dorms from 28,30 EUR including breakfast and linen, various concession apply. Towels can be rented from the reception for additional 2 EUR.edit
Hotel ISG, . Hotel ISG is located in the suburb of Boxberg is about a 15 minute taxi ride from central Heidelberg. Fitted out in the Bauhaus style the rooms are comfortable enough (and the bathrooms are excellent) but there is nothing to do in Boxberg.edit
Hotel Restaurant Scheid. Hotel Restaurant Scheid is a nice, quiet, reasonably priced hotel in the suburb of Schriesheim, a short tram ride north of Heidelberg. Schriesheim is built on a hill so if you are hitting the clubs, don't forget about the late 30 min. night walk up the hill from the tram stop (Schriesheim Bahnhof) to Hotel Scheid. Phone +49 (0)6203 6050.edit
The Ritter, Hauptstraße 178, (firstname.lastname@example.org), . The Ritter is the oldest building (1592) in Heidelberg that has outlasted all fires and wars that have haunted the city over the times. It can get a little noisy considering its location directly at the heart of the Altstadt. Also a picturesque photo opportunity. edit
Hip Hotel, Hauptstrasse 115, . This was revamped in 2005 as a boutique hotel. Each room is modeled after a famous city, the most interesting room being the Zermatt (for Heidi and skiing fans).edit
Hotel Neu Heidelberg, . Hotel Neu Heidelberg is located in the west of Heidelberg's center. Recommendable 3 star hotel with lovely restaurant, nice breakfast buffet, terrace, garden, wlan, bicycles for guests, free parking, various int. tv channels, etc. Easily reachable by car and public transportation.edit
NH Hotel Heidelberg, . Located about 1km west of the edge of the Altstadt, situated in an old brewery. However its been totally renovated and fitted out in a modernist decor, all glass, wood floors and exposed metal. Some of the rooms are very pleasant, though the ones overlooking the main road can be noisy. Food in the bar is disappointing.edit
Crowne Plaza, . A fairly standard anonymous business hotel is located just off Bismarckplatz. Rooms near the lifts can be extremely noisy, so are best avoided.edit
Holiday Inn Heidelberg, Pliekartsfoerster Strasse 101, (toll free: 0800181 6068), . checkin: 3PM; checkout: 11AM. Standard hotel that's about 5 kilometers outside of the center of Heidelberg. Amenities include a sauna and gym. Internet access comes at a hefty minimum price of €10 for 60 minutes or €17 for 24 hours if travelers are only looking to browse. For business users, it's even more expensive. €198 +. edit
Hotel Holländer Hof Heidelberg, Neckarstaden 66, Tel: +49/6221/60 500. The hotel has a unique view of the Neckar River and the Philosopher´s Walk. It is located in the middle of the historical old city centre, just opposite the Old Bridge. The famous Heidelberg castle, as well as all sights of Heidelberg can be reached within a few walking minutes. The Restaurants and the pedestrian area are located around the corner.
Der Europäischer Hof, . Located just on the edge of the Altstadt Der Europäischer Hof a classic privately owned five star hotel. Pleasant atmosphere and attentive staff. Most of the rooms look out over the courtyard and are therefore admirably quiet. Since 1865 der EUROPÄISCHE HOF has been a home from home for cultivated travelers in search of timeless traditional charm, atmosphere, and service. The name of the establishment stands for all that is best in European hotel culture and for exceptional standards of service. Official listings have rated the hotel as the finest hotel in Heidelberg and in the Rhine-Neckar Metropolitan Region. The hotel is a Certified Business Hotel, Certified Conference Hotel, and certified as conforming to the pharma code. Accordingly, they have everything you expect of a professional business hotel. edit
Hirschgasse Heidelberg, Hirschgasse 3 - 69120 Heidelberg, ☎ +49 6221 4540, . checkin: 3 PM; checkout: 12 AM. The Hirschgasse is the oldest Hotel of Heidelberg and the oldest student dwelling house of Germany. It was first mentioned in a love story in 1472 and is nestled in a little side valley of a select residential area opposite the Heidelberg castle. An impressive walk along the River Neckar will take you to the Altstadt on the other side of the river. Mark Twain wrote about this in his book "A Tramp Abroad." The rooms are all unique and will delight Laura Ashley fans and the ones seeking a good shot of authentic romantic ambiance. It comes along with two restaurants: the historic Mensurstube with regional dishes and over 250 year old tables, even Count Otto von Bismarck carved his name into. The elegant Le Gourmet is a classic French restaurant with attentive but yet uncomplicated service and will delight your credit cards with a good value for a swipe. A vineyard only a stone's throw away from the hotel "Sunnyside upon the Bridge" provides a good local Riesling or Late Burgundy.from 125 to 335. edit
Weinheim - A small city between Darmstadt and Heidelberg
Dilsberg / Neckarsteinach - has four small castles in a row. Dilsberg's castle has a well which is accesible by a tunnel. Neckarsteinach's railway station is 20 mins away taking the S1 or S2 train from Hauptbahnhof or Karlstorbahnhof. From there it is a 5 km walk on a forest trail to Dilsberg, a medieval village with a town wall. The Dilsberg youth hostel is in the old city gate.
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