Located 50 kilometers northwest of the downtown Beijing, noted as the 13 Tombs , this is the burial area of 13 out of 17 emperors of the Ming Dynasty, the ruling dynasty of China from 1368 to 1644. It was the final dynasty in China administered by ethnic Hans. At present there are only three tombs which have been dug and open to the public: Dingling Tomb, Zhaoling Tomb and Changling Tomb. Changling Tomb is the first tomb to be excavated. It took two years for the digging and restoration, and was opened in 1958. Dingling has been excavated so completely that people now have to go into the burial chamber itself. However, it is a very deep climb down and people with problems of their heart or kneels are not advised to visit the underground tomb. Wheel-chair users or people with some difficulty of action, I advise them to visit the Changling Tomb instead. Zhaoling Tomb is where Zhu Zaihou, Ming Dynasty's (1368-1644) twelfth emperor and his three empresses are buried, its structure remains the same as the other ones and it is the first that has been restored.