Back in 2015, before he launched his Patreon campaign, WW2HistoryHunter added an incredible video to his popular channel. Apparently, while traveling through Germany he had stumbled upon an astonishing secret, hidden away in an undisclosed location.
In the video, WW2HistoryHunter can be seen exploring a forest thick with autumnal trees. There, totally camouflaged by its surroundings, the viewer can just make out the outline of a roof. On closer inspection, the camera reveals rugged walls, formed from a mixture of concrete and cement.
Suddenly, a hole opens up in the undergrowth. The camera pans across it, revealing what the subtitles claim is a ventilation shaft. Sure enough, the cavity is seen to stretch far off into the darkness below. Next, the video reveals what looks like an entrance, bricked up and camouflaged with undergrowth.