Simatai, built during the reign of Ming dynasty emperor Hongwu, is famed for the precarious steepness of its battlements as they soar up the 'heavenly ladder' of the Yan Mountains. Heavily restored and reopened in 2014, its once rambling charm has been diluted by the faux-historic Gubei Water Town, although an admittedly nice feature is how part of the Wall is illuminated (and can be walked on) after dark.
Note too that since the Simatai renovations, it is no longer possible to hike west to Jinshanling. The route east too is shorter than it used to be, with only 10 watchtowers open at the time of research. If you only want to visit the Wall and skip the Gubei Water Town, you need to reserve tickets in advance at www.wtown.com, which can then be paid for on entry.
There are some unusual features at Simatai, such as ‘obstacle walls’ – walls within walls used for defending against enemies who had already scaled the battlements. Small cannons have been discovered in this area, as well as evidence of rocket-type weapons.
A short section of Simatai Great Wall is illuminated with lights inset into the battlements, and opens after dark (6pm to 10pm). At this time it's mandatory to use the cable car both ways, which bumps up the cost.
From Dongzhimen Transport Hub, a tourist bus (¥48, two hours) leaves for Gubei Water Town four times a day at 8am, 9am, noon and 3.30pm, with an extra 2pm bus on weekends and holidays. Returning buses are at 1pm, 5pm and 9pm, with an extra bus at 7pm on weekends and holidays.