1. The Buffa di Perrero Shelter, Italy
Imagine stumbling upon a tiny house clinging to a sheer cliff, 9,000 feet high in the Italian Dolomites; that’s Buffa di Perrero, the so-called world’s loneliest house. Built by Italian soldiers during World War I, this hidden shelter was carved into the mountain for rest and survival during fierce battles.
No roads, no paths; only rope ladders and daring climbs could reach it, making it one of the most mysterious and daring feats of wartime engineering.