From 1932 to 1990 the city was known as Gorky (Го́рький), after the writer Maxim Gorky. Following the fall of the Soviet Union, the old name was restored.
The city was founded by Grand Duke George II of Russia in 1221 at the confluence of two most important rivers of his principality, the Volga and the Oka. Its name literally means Newtown the Lower, to distinguish it from the older Novgorod. A major stronghold for border protection, Nizhny Novgorod fortress took advantage of a natural moat formed by the two rivers.
Along with Moscow and Tver, Nizhny Novgorod was among several newly-founded towns that escaped Mongol devastation on account of its insignificance and grew up into important centers of Russian political life during the period of Tatar yoke. For a short period of time it was the capital of the Suzdal Principality and competed with Moscow for the power in the region. However the competition with Moscow was lost and in 1392 the city was incorporated into Muscovy. Nizhny Novgorod Kremlin was built in 1508-1511 (under supervision of the Italian fortress engineers) and became one of the strongest Russian citadels. There is a legend saying that the project was initially developed with participation of Leonardo da Vinci. However there is no documented proof of Leonardo's work for that project, the only thing the legend is based on is the striking resemblance of Leonardo's sketches and the actual kremlin schemes. The fortress was strong enough to withstand Tatar sieges in 1520 and 1536.
In 1612, the so-called national militia, gathered by a local merchant Kuzma Minin and commanded by Knyaz Dmitry Pozharsky expelled the Polish troops from Moscow, thus putting an end to the Time of Troubles and establishing the rule of the Romanov dynasty.
In 1817, the Makaryev Monastery Fair, one of the liveliest in the world the 16th-18th centuries, was transferred to Nizhny Novgorod, which thereupon started to attract numerous visitors and by the mid-19th century it turned Nizhny Novgorod into trade capital of the Russian Empire.
Under the Soviet rules the trade connections of the city were abandoned and Nizhny Novgorod turned to become an important industrial centre instead. During the communist time the city was closed to foreigners to safeguard the security of Soviet military research. The physicist and the Nobel laureate Andrei Sakharov was exiled there during 1980-1986 to limit his contacts with foreigners.
The climate in the region is humid continental and it is similar to the climate in Moscow, although colder in winter, which lasts from late November until late March with a permanent snow cover.
The city is divided by the river Oka into two major parts: the Upper city (Nagornaya chast) on the hilly right side and the Lower city (Nizhnyaya or Zarechnaya chast — what literally means "the part over the river") on the left bank of the river. The Upper city is the old historical part of Nizhny Novgorod, whereas the Lower city is larger, newer and consists of more industrial districts.
The Upper city is administratively divided into three districts (rayons):
The districts of the Lower city:
Wikitravel has a guide to Trans-Siberian Railway.
Trains are probably the best and the most convenient way to get to Nizhny Novgorod. Most of the Trans-Siberian trains (including the legendary train No.1 between Moscow and Vladivostok and the train from Moscow to Beijing) pass via Nizhny Novgorod.
By train from Moscow:
The fastest option is to take Sapsan  that will carry you for 3h 55m (departure from Moscow's Kursky station twice per day, one early at the morning, the other at evening). The other option is Burevestnik express which commutes between Moscow and Nizhny Novgorod twice per day (departure from Moscow's Kursky station). It will take around 4 and a half hours to get Moskovsky station in Nizhny. There are also comfortable overnight trains departing from Moscow's Kazansky station and from Yaroslavsky station. Of course it is possible to use other trains going eastward departing from various Moscow's stations.
By train from Saint Petersburg: the night train "Volga" departs each evening and arrives to NN next morning.
There are also direct train connections with Kazan, Samara, Kirov, Yaroslavl and other cities of the region (there are mainly night trains). As well as with Vladivostok, Beijing, Ulaanbaatar, Irkutsk, Astrakhan, Simferopol, Novorossiysk and many others.
The international airport of Nizhny Novgorod (GOJ) is situated in Strigino district what is about 30-40 minutes by taxi from city centre (if there are no traffic jams). The airport is rather small. There are several daily flights to Moscow, also there are domestic connections with Chelyabinsk, Mineralnye Vody, Rostov-on-Don, Samara, St. Petersburg, Sochi, Surgut and Yekaterinburg. International connections include Baku (Azerbaijan), Dubai, Dushanbe, Frankfurt (Germany), Helsinki (Finland), Prague (Czech Republic), Tashkent and Yerevan (Armenia) as well as various seasonal charter flights to resort destinations, mainly in the Mediterranean. Most of the flights are operated by the Russian airlines, but flights to Frankfurt are by Lufthansa and to Helsinki by Finnair and Prague by Czech Airlines.
You can get to the airport by buses number 11, 20, T-29, T-46 (20 rubles in July 2012) or by taxi (normal price from city centre will be around 700-1000 rubles or $25-$30 US).
Nizhny Novgorod is situated on M7/E30 road. The road is quite ok and it usually takes about 4 hours to get to Nizhny from Moscow. However the traffic jams in the suburbs of Moscow can make the way longer. The story about speed regimes and the road police will follow soon ...
There are regular state-owned daily bus connections with Moscow (from Kanavinskaya bus station in Nizhny to metro Schelkovskaya in Moscow) but the buses are very slow (it can take up to 10 hours with several stops in all the towns along the road) and rather uncomfortable. There are also faster private daily and overnight buses between Kursky railway terminal in Moscow and Moskovsky railway terminal in Nizhny Novgorod.
River cruises  ] down the Volga operate during the summer months (early May to end of September). Dozens of boats operated by different companies run from Moscow to Astrakhan and back. One way or return cruises may be reserved to/from practically any city along the Volga.
The (quite out-of-date) map of transport routes could be downloaded here: 
2GIS site has an up-to-date (and often updated) information on all transport routes, together with route planner:  (in Russian, but just click on the map and on the pop-up use "Маршрут отсюда" for source and "Маршрут сюда" for destination).
There are two lines in Metro, both connected in Moskovskaya station. The first line goes from Burevestnik. The second one goes to Park Kultury. Several stations are going to be built. Working hours: 05:15am - 12:00pm. Price: 16RUB. Railway station is above the Moskovskaya station.
A new segment from Moskovskaya across the river to the Gorkovskaya at the city center was opened in November 2012.
Car rent that locates in an airport and in the central station is "Paulz" (http://www.paulz.ru) Phone: +7 (831)4136208
Tram communications were opened in 1896 and now there are about 30 lines operating in the city.
Extensive network of 25 lines.
About 80 lines of government-owned buses.
Also about 80 lines of privately-owned buses calles marshrutnoe taksi (literally routed taxi) or marshrutka. These are generally smaller than government-owned buses and usually (but not always) feature a letter "T" before the number of route. Note that they have different routes from that of government buses, so a bus and a marshrutka with the same number have usually completely different route. Note also that in contrast to other public transport, these do not stop at every stop; to indicate your intention to exit a marshrutka, you should press a button above the door, and to indicate your intention to enter an oncoming marshrutka, you need to wave your hand.
On surface public transport (trams, trolleybuses, buses and marshrutkas) you are expected to pay within one stop after you enter, the fare is fixed for one ride. Some vehicles (almost all trams and trolleybuses and about a half of buses and marshrutkas) have a special man called konductor who will come to you, take money and issue a ticket; if there is no konductor, you should pay directly to the driver. Both the driver and konductor will give change if needed, although large notes (1000 and 5000 RUB) can sometimes be denied.
If it is crowded, it is customarily to ask other passengers to pass your money to a driver or konductor (however, if a vehicle has a konductor, he/she will usually find a way to you unless the vehicle is indeed completely packed). This is safe and money losses are very rare (and in most cases unintended), although it is better to pass the exact amount so that no change is needed, or at least not pass large notes. In any case, it is better to prepare you money before entering a vehicle.
Note that the walks on the Kremlin's wall are cariied out from 1, May to 1, October.
Take a ride on the new cable-car from Nizhny to Bor on the other side of the river. The station is a bit hard to find, but if you walk along the Volga eastwards you can see the cables spanning the river. Just walk along the bank and you will find the station hidden behind some newly constructed building.
Cross the river and ejoy the great view. There is not much to do in Bor, except for if you like Russian suburban tristesse. One ride is 80 Rubles.
If you are planning to spend in Russia more than several days and you are going to communicate with your Russian colleagues by mobile (and send SMS to your home country) it would be reasonable not to spend on roaming and to buy a local SIM-card. There are five GSM networks in the city: three major Russian mobile networks ("big three": MTS, Beeline and Megafon), Tele 2 and NSS (HCC). Also there is a network working in AMPS/DAMPS standard and there was one in NMT-450 (not sure if it's still there). The prepaid tariffs are more or less the same in all GSM networks. A SIM-card can be purchased in numerous shops, kiosks, and special salons. Usually it costs you just to pay some 3 or 4$ for your future calls.
However if you come to Nizhny Novgorod with a SIM-card bought in Moscow or Saint Petersburg be aware that you will be charged higher prices for your calls since providers consider this as inner-Russian roaming (basically the country is divided in several huge roaming zones). Mobile numbers registered in Nizhny Novgorod are of the Volga region zone.
There are payphones in the streets however you can buy phonecards only in the post-offices and in few newspaper kiosks.
By internet and wi-fi
There are several wi-fi spots for free internet access in the city. For example, there is wi-fi coverage in the cafe at KARO cinema on the top floor of "Shokolad" (Chocolade) shopping-mall in Belinsky Str. Free Wi-Fi (with the purchase of a meal/drinks) is also available at a cafe called "Artbus" ("Артбус", wordplay on the Russian word for "watermelon" - "arbuz"). Be aware, though, that this cafe has a monthly bandwidth limit, so if you try to use the Wi-Fi there toward the end of the month, you may not succeed.
In the Upper city (Nagornaya chast' Нагорная часть):
In the lower city (Zarechnaya chast' Заречная часть):