The salt cathedral of Zipaquirá is one of the most interesting places I have ever visited. It's a working salt mine carved several hundred meters into the Earth that has, in time, also been turned into a full Catholic Cathedral.
The workers believed (and still do) that they needed god's help protecting them from the dangers of the salt mine and thus carved out all of the rooms by hand over many years.
There is a complete fourteen step story of Jesus' death and an amazing mass hall.
