Colombia's Salt Cathedral

In 1995, a cathedral was built 180m underground in the Zipaquirá Salt Mine in Colombia.

The idea came from the miners building makeshift altars in the mine in the 1930s, to pray for their safety before starting their shifts.

It’s now a major tourist attraction, attracting more than 600,000 visitors a year.

Rachel Naylor speaks to the engineer behind it, Jorge Enrique Castelblanco.

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(Photo: Tourists in the Salt Cathedral of Zipaquirá. Credit: Phil Clarke Hill / In Pictures via Getty Images)