A chunk of the Great Wall of China has reemerged after being submersed in water for four decades.

The section of the wall in Kuancheng Man Autonomous County, Hebei Province was submerged under water after a reservoir was built for hydroelectric power plants downstream in the 1970s. However, a recent drought has seen these water levels decline, revealing a section of brickwork and towers that has remained in remarkably good condition.

The Great Wall of China remains one of the largest construction projects ever undertaken, spanning a massive 21,196 kilometers (13,171 miles). But the wall is actually a series of separate walls built over a period of thousands of years as a defense against invasions of nomadic groups, and it helps the authorities apply duties on goods transported along the Silk Road.

This recently revealed section of the wall was part of the construction by the Ming Dynasty around 500 years ago, which remains one of the most extensive and well-preserved portions of the wall.