Some dads build their kids tree houses, but in the treeless desert of southeastern Utah, Albert Christensen's only possible alternative was a cave. Christensen blasted the rocks off a sandstone cliff face, so that his sons could sleep at night.
He continued drilling and expanding the cave for 12 years until it was large enough for both him and his wife to move in in 1952. Albert was building a 100-foot tall staircase when he died. The stairs would have cut up to the top of the rock, where his wife would have arranged a rock garden.