Three Days in Beijing
See the main Beijing article for information on how to get to Beijing and how to move around within.
Other than the Great Wall, most of this itinerary can be covered on foot, with few subway rides to starting points and back. However, distances in Beijing are generally far, and some may prefer taking a taxi for parts of the itinerary. See the main Beijing article about how to get around in the city.
If you are still not too footsore, head east from Jingshan and straight into one of the narrow Hutong areas (e.g. at Jingshan Dongjie), and keep going east until you come upn the next major road, Beiheyan Dajie. Parallel to this runs a narrow strip of green park due south. Enjoy the park for about half an hour's walk until you come to Dong'anmen Dajie, and go east for one more block to the Donghuamen Night Market.
Conclude your first day in Beijing with some tasty snake or scorpion at one of the stalls, or have some other more 'mundane' dinner in one of the restaurants.
Head towards the Great Wall. Check out the special article about the Wall, and also have a look at The Great Wall Forum, which has many helpful tips about many sections of the Wall and how to explore them.
It's easiest to simply book a guided tour to the wall, but be sure to do it at a reputable travel agent or the tour desk at your accommodation. There are many, many rip-offs and crappy tours but if you book thru a reputable travel agency or thru your hotel, you are likely to have a great experience. Especially if short on time, confirm whether the itinerary contains shopping or other unwanted time-wasters. Many tours also include a trip to the Ming Tombs (which are recommended to see) but not compulsory.
If you are a little adventurous and want to see a part of the Wall that's (much) less frequented and also less restored, take a tour to Jinshanling. While that's about a three-hour drive one way, you will be treated to many breathtaking views and a chance to take a long hike with very few people around (maybe about 2-3 tour buses for the whole day). Tours are about ¥230 with two meals, plus ¥50 entrance fee. If you are fit, there is no need to spend another ¥50 on the cable car, as the wall can be reached in about 15 minutes on foot.
If you decide to take a tour that doesn't last the whole day, you might also consider checking out the Ming Tombs or the Olympic Park in the afternoon.
An event that is seemingly quite popular among domestic tourists, but much less so among foreigners, is the Flag Ceremony at Tiananmen Square at sunrise. If you feel like, get up early enough and make your way to Tiananmen Square (also a nice opportunity to see Beijing rather deserted) before sunrise. Try to be a bit early if you actually want to see the ceremony through the crowds. The whole event, however, takes less than 15 minutes and the crowd is rather intent on taking many pictures as opposed to cherishing this solemn patriotic moment.
After this early start, you may want to crash at your accommodation for another hour or two, or find some place to have coffee and breakfast (most of Wangfujing St is closed, though, except some McDonald's and KFC places). Once the stores open, take some time to shop for souvenirs before the crowds start pouring in.
Later in the morning, resume sightseeing at the Lama Temple (Yonghegong), which you can easily reach by metro line 2 (take the south-east exit). The temple (¥20 admission) is a fairly big complex with several gates and halls with countless Buddhas and other figures. The largest of the statues is at the very back of the temple, an 18-m Buddha figure that fills a large building up to the ceiling. The place shouldn't take more than an hour to explore.
From the Lama Temple head west (only a few hundred meters) until you reach Confucius Temple (¥25 admission, student discount available), which is much more quiet compared to where you have just been. Be sure to also check out the adjacent academy (first gate on the left, after you enter by the main entrance), which is even less frequented and also boasts some richly decorated beautiful halls and beautiful reflections in the small moat.
Continue heading west from Confucius temple and you enter one of the more popular Hutongs (=traditional neighborhoods with narrow alleyways and winding lanes). This is a great area to explore just randomly, and also to have some coffee or a little lunch. Try not to get lost, as it is very easy to walk in circles and those tiny streets are not to be found on any map.
Heading west you finally arrive at the last sight of your trip Drum and Bell Towers (near Gulou Dajie), which are again popular among tourists, and thus slightly crowded. Once you have had enough, you can catch the metro at Gulou Dajie station (10 min walk north of the towers). Depending on how and when you started the day, it may now be around 2:00-4:00pm. Don't miss your plane.
Stay away from touts offering rides on three-wheeled vehicles.
Also, avoid scams around Tienanmen Square. Chinese men or women on the subway or the square will approach you with basic greetings (How are you? Where are you from?), ask routine conversation questions ("When did you get here? How long will you be here?" etc.), then direct the conversation to getting tea/coffee/beer at a place of their choosing. It may seem innocent and fun, but they will order everything without you being aware of any prices, then as the bill arrives, they will try to force you to pay a very inflated price in full. To compensate, they may "arrange" to have the restaurant provide a souvenir which is "fen to the yuan" and attempt to make it look like they're not doing to what in fact they are -- ripping you off by taking advantage of your lack of traveler's sense. To avoid this, utilize common sense and keep to yourself. You will not have made a new Beijing bestie; you will have helped the restaurant's bottom line as the two are most certainly operating in cooperation with one another.