Zipaquirá's stunning Catedral de Sal, 190m underground, was carved by removing 250,000 tons of salt; the resulting space is cinematically lit and packs a lot of ecclesiastical wow throughout its cavernous chapels and naves. It's highlighted by the largest cross ever built in an underground church. Visitors must join regularly departing hour-long tours – you can leave them once you're inside if you want. The walk leads past the 14 stages of Jesus' crucifixion, the illuminated cupola and, finally, the stunning nave.
The tradition of mixing religion with salt has logical roots: work in the mines was dangerous, so altars were made. The 75m-long mine can accommodate 8400 people and holds services on (very busy) Sundays, though, lacking a bishop, it has no official status as a cathedral in Catholicism.
Admission includes other eminently skippable Parque de la Sal attractions like a light show, a 3D film and a brine museum.