The Chapel of St. Kinga, Wieliczka Salt Mine, Poland (13/20)

Tucked 101 meters (331 feet) beneath the earth’s surface in the Wieliczka Salt Mine, the Chapel of St. Kinga is an extraordinary subterranean marvel. Carved entirely out of salt, including the chandeliers, altars, and sculptures, the chapel is an otherworldly space that blends art, religion, and geology in a truly unique way.