Tour operator Albatros Travel is gearing up for its annual Great Wall Marathon. On May 21, participants will run a full marathon (42.195km), the half marathon (21.1km) or a fun run of 8.5km. It's not going to be an easy run as the wall slopes up and down, and there are stairs (the horror!) to climb as well. The views are amazing, though, and if you're running the full marathon, you will pass by four villages and the lower valley. 

If you don't already live in China, the run is part of a seven- or six-day package (about $1,804-2,100) respectively from either May 17 or May 18 onwards, with the run being the last thing you do. International flights are not included, but it's a pretty thorough introduction to Beijing (that is, if it isn't covered in smog).