Ｋｕｂｌａｉ Ｋｈａｎ’ｓ Ｓａｆｅ Ｈａｖｅｎ

ＴＡＮＧ　ＹＵＡＮＫＡ

Built to protect the capital of the Yuan Dynasty, Beijing'scity wall is now a tourist attraction and a safety shelterin times of disaster.