Guguan Pass is located 35 km (21.7 miles) away from the Pingding County in Shanxi Province. It was initially built in 333 BC and reconstructed in the Ming Dynasty (1368 - 1644), and became the first defensive line for the capital of the Ming Dynasty. The southern section of Guguan wall totals 7,000 m (4.3 miles) from the Jiangjuyu to Baihuikou, and the northern section is 13,000 m (8.1 miles) long from Cenhoudi to Niangziguan. As one of the well-preserved stone walls in China, Guguan was built with many defence facilities like beacon towers, watch towers and batteries.