Cycle the Ming City Wall

Xi'an's Ming-dynasty rampart is the most complete ancient city wall in China — a 14km rectangle, 12m high and wide enough to drive on, enclosing the old town. The move is to rent a bike at the South Gate (Yongningmen) and ride the full loop; a relaxed lap takes 90 minutes to two hours, with watchtowers and gate complexes to stop at along the way. Sunset and the post-dusk lantern-lighting are the prettiest windows. There's a two-hour limit on the rental bikes, which is plenty for one circuit.