Rothschild Mansion in Paris. The neo-Louis XIV castle has been abandoned since the Second World War when the Rothschild family fled to England before the arrival of the Germans, who would later inhabit and plunder the house during the four-year Nazi occupation of Paris. The Rothschilds never returned to their home and over the decades it has been left to deteriorate.
Journey into the Dystopian World of Abandoned Soviet Submarine Bases
You've entered an enormous building scoured by ocean tides and haunted by hulking machines, slowly rusting away. It looks like the set for a post-apocalyptic movie, but it's actually a real-life Soviet submarine base, left over from the Cold War.