If you are planning on taking the subway line 13 to Longze - the instructions above are correct but here's the rest. First, when you exit the subway station at Longze, the bus station is across the street and just to the right. The number 20 is clearly marked. The bus ride out is about 1 hour and 20 minutes long - go to the end of the line in Nankou - the cost is 5 RMB per person - the last bus leaves Nankou at 8pm. When you get there you will see a street sign at the intersection indicating that Juyongguan is 8km from there. There you will have two options: (1) catch the number 68 bus to the Great Wall (last one leaves the wall at 8pm), or (2) take one of the private taxis that will most likely approach you when you get off the bus. The private taxis will charge somewhere between 10-30 RMB. I took the taxis and got to and from the wall with no problem. Once you arrive at the Great Wall, you can go east or west on the wall. The west side is where all of the shops, restaurants, and tourists are located. If you hike the wall in that direction you will reach the end (literally the wall ends with a small terrace) after about an hour (depending on how fast you move). That is also the steeper side, but the view from the top is great. Otherwise, you can go east. The east side is relatively free from people and is a much easier hike. There are no shops on the east side. Both are very cool. Hope this helps, we figured it out by asking various people along the way.