Three Gothic Revival-style buildings, located on a 50-metre (165-foot) bluff overlooking the Ottawa River, house the offices of the members of Parliament, the House of Commons and the Senate. Free guided tours examine Canadian history and explain the workings of the political system. Canada’s stone Parliament Buildings are decorated with intricate carvings, gargoyles and friezes. They’ve been referred to as the “purest example of Gothic Revival architecture” in the Western hemisphere. The original Centre Block of the Parliament Buildings burned down in 1916 in the midst of World War I, though the cause of the fire has never been discovered. Theories of enemy conspiracy abound, but the most likely cause was a cigarette in the Reading Room.