Beijing: the Forbidden City needs your passport; the Great Wall, a choice

The Forbidden City sells a limited number of tickets per day, bookable online a week ahead with your passport number, and it's closed on Mondays; the passport is scanned at the gate. For the Great Wall, Badaling is the closest and the most crowded; Mutianyu has a cable car and fewer people; Jinshanling is a real hike. Skip the "tea ceremony" invitations from friendly students near Wangfujing and Tiananmen, which end in a huge bill.