For Hitler's 50th birthday in 1939, the Nazi Party gave him a mountaintop house called the Kehlsteinhaus. The world knows it as the Eagle's Nest. Building it was insane. Around 3,000 workers carved a 6.5 km road into the side of the mountain in roughly 13 months, working through brutal Alpine winters. Several of them died doing it. At the top of the road, you walk into a tunnel bored straight through solid rock. At the end is an elevator lined with polished brass that shoots 124 meters up through the inside of the mountain and opens directly into the house. Inside, the main room had a red marble fireplace that was a gift from Mussolini. And Hitler barely used any of it. He was uneasy with heights, nervous that lightning would strike the elevator, and complained that the thin air at 1,834 meters bothered him. Historians estimate he went up fewer than 20 times. He much preferred his house at the Berghof down below. The person who loved it was Eva Braun. Her sister Gretl's wedding reception was held there in 1944. In April 1945, the RAF sent hundreds of bombers to flatten the Obersalzberg complex. The Berghof was wrecked. The Eagle's Nest, sitting alone on a peak, came through basically untouched. Today it's a restaurant and beer garden. Tourists ride the same brass elevator, and the profits go to a local charitable foundation. The most famous Nazi retreat in the world ended up serving cake to tourists for charity.