The Great Wall is approximately 4000 miles long and dates back to the 5th century. It originally began as independent walls constructed by various states who believed they enemies or were having problems with neighbors. During the Qin Dynasty it became the "great" wall with individual walls be joined with the Huns being the foe after China’s unification.
Badaling located 47 miles nw of Beijing is the most crowded. This section of the wall includes restored towers and turrets, a museum that shows a 15 minute video of the wall, and a cable car. Tours typically give you about 2 ½ hours to explore. The cost is Y40.
Mutianyu was opened to relieve some pressure off Badaling although it has begun to get crowed as well. Like Badaling this section of the wall has been restored and again tours are usually 2 ½ hours long. The cable car is Y35 one way and Y50 round trip with entrance to this section Y35.
Both Badaling and Mutianyu are the relatively close to Beijing and half day tours are offered to both or can be combined with a visit to a tomb. On the other hand, the following sections of the wall involve a three hour drive one way with walking and hiking necessary on rough terrain.
Simatai is 67 miles ne of Beijing and not restored. From the entrance there is the choice of hiking towards the left towards Jinshanling or to the right which is the very steep and can require climbing on all fours depending on how far you go. Tours are not readily available, but mini bus transportation can usually be arranged at hotels for Y80 with the entrance another Y30.
Huangyaguan is 18 miles nw of Huairou and is not restored. The reservoir, water pass and beacon tower along with the yellow leaves in the fall (hence the name) provide the uniqueness to this section. Entrance is Y15. There are no tours for this, but 2 bus routes followed by a mini bus will get you there.
Jinshanling is the least visited section but the best preserved (not to be confused with restored). It is 94 miles from Beijing and includes highlights such as 67 watchtowers with 7 miles, a storehouse tower and obstacle walls which are walls within walls. Aside from public transportation, there is are usually mini buses arranged at hotels for transportation only for Y90. The entrance is Y30, but halfway to Simatai you have to pay Y30 again for the Simatai section.