There was so much rubble in Berlin after WWII, they could've built a mountain from it. Well....actually, they did. And named it, "Devil's Mountain". Teufelsberg (its German moniker) today looks like any other massive hill, covered in shrub, tree and grass. Crisscrossed with hiking paths. But beneath...beneath lies 98 MILLION cubic yards of brick and debris. They pilled up so much shit it created the tallest point in West Berlin. I was told women were largely responsible for the effort, but can't confirm. It gets wilder. Beneath the rubble is a Nazi military technical college. Allied forces discovered the under-construction facility....tried to demo it with explosives...but it was so sturdy that covering it was actually the best option!! Still better... Decades later, as the US and Russia ramped up the Cold War efforts, the United States NSA built a massive spy station on the hill. Part of a larger listening and intelligence gathering network named ECHELON. It's a massive complex of buildings, towers and domes. Now abandoned, these structures still stand. The best part yet...they are covered wall to wall with graffiti. Everything. The domes, the towers, small sheds, full warehouses. It's fucking amazing. Some dude will try and collect 10 euros or something to get in there, but there's ways to sneak in for free. It's one of those things that would be completely illegal in the US...or likely never exist. The views from atop the towers are sweeping, and grand. It's unlike anything I've ever seen abroad.