where is xuan wu gate, to take bus (no. 12) to simatai (great wall)?

Buses from Xuanwumen to Simatai are available, but it is not bus no. 12. Tourist buses operated by the local Tour Dispatch Hub leave from Xuanwumen (the northeast corner of the crossing of Xuanwu Gate, the parking lot outside the Cathedral Church). Buses leave at 08:00 during May 23 and Oct. 10, on weekends and Chinese holidays.