Beijing's subway system has literally evolved from a two-liner (i.e. lines 1 and 2) to what is today one of the most extensive subway networks in the world. Many say that no matter how many more lines the subway adds, the mayhem on the roads will not subside. However, imagine what was to happen if the subway system closed overnight. Just have a look at the hordes of people taking the subway every day and you will thank the Gods for it being there.
A modern subway line in Beijing (caption)
Subway because it is underground
As is defined by its name, the Beijing subway mainly operates under the earth, with the airport express, line 13 and some of the suburb lines representing the big exception. While in larger cities around the world there are subway tracks interwoven with the downtown landscape this would be hardly imaginable in Beijing. It is simply all too clustered.
You may be laughing now…
The lay of the land
As mentioned above the Beijing subway started out with two lines still operating today. Line 1 goes east to west and vice versa while line 2 is the circle line roughly following the second ring road. Today, there are another 10 or so lines (number constantly changing) zigzagging the city in all possible directions. Ever since the Olympics the subway administration has spent a lot of effort to bring the signage in the stations up to speed, so even foreigners should have a hard time getting lost. If you do, please remember that once you enter the system and have paid your fare you can take almost as much time as you want to get out again. The price will stay the same.
PS: You are also advised to get a traffic card for the subway but for some reason no discounts apply here.