This fascinating museum in the stunning Main Post Office building explores postal history in imperial China, which dates back to the 1st millennium BC. The system used an extensive pony express to relay messages; Marco Polo estimated there were 10,000 postal stations in 13th-century China. Check out the collection of pre- and post-Liberation stamps (1888–1978) in a special climate-controlled room. You can also inspect a historic mail-train carriage and two old post vans, one horse-drawn, plus a recreation of a Qing-dynasty mail room.