Work on a nature restoration project in Belgium unearthed multiple bunkers, trenches and other structures built there by the German army during World War II, officials announced, reports CBS News.

The restoration work is being done at the Director-General Willemspark in Heist, Belgium, and focuses on restoring coastal dunes in a less than one square mile area by removing invasive plants. 

Several structures from the World War II stronghold were found preserved in the ground, including "three completely intact bunkers" covered under just a few inches of dirt. Each bunker had just one room, but was built with walls and a ceiling of reinforced concrete.

Officials also found two brick trenches, a fragment of concrete track that would have been used to ferry soldiers and supplies during the war, and a water well. During the excavations, workers also found "large mountains of rubble" that contained everyday objects like utensils, ammunition, and more.

The Heist park, also known as Heist-Aan-Zee, is in the northern Flanders region of Belgium. The area was the site of multiple battles during World War I. But in 1942, the park was again converted into a military stronghold by German soldiers.