The Southeast Corner Watchtower, or better known as the Dongbianmen, dates back to the early years of the Ming Dynasty, it was built in 1436. It is the largest remaining corner of the former defences of the city. The tower is built upon a rectangular stone platform and stands 30 meters higher than the actual wall. Visitors can go into the tower where they will find an exhibit of historical relics which gives them an idea of its political, military, economic and social state of the time. The lower floors of the tower is the Red Gate Gallery which is the leading art gallery of contemporary Chinese art.