Hotel Alcatraz

Some hotels are built with living trees as structural elements, for example the Costa Rica Tree House in the Gandoca-Manzanillo Wildlife Refuge, Costa Rica; the Treetops Hotel in Aberdare National Park, Kenya; the Ariau Towers near Manaus, Brazil, on the Rio Negro in the Amazon; and Bayram's Tree Houses in Olympos, Turkey.
Bunker hotels
The Null Stern Hotel in Teufen, Appenzellerland, Switzerland and the Concrete Mushrooms in Albania are former nuclear bunkers transformed into hotels.