An 18th-century Spanish watchtower made entirely of seashell and concrete.

This church, buried halfway in lava rock, is all that remains of a Mexican village destroyed by a volcano.

A Gothic cathedral created from volcanic rocks.

Oldest existing church in New York and the inspiration for Washington Irving's "The Legend of Sleepy Hollow."

Mountain where Jesus was first tempted by the Devil.

Sanctuary on a ridge near an ancient shrine to a "Black Madonna" built by the founder of Opus Dei.

This 16th-century monastery has been turned into a surrealist architecture compound.

Possibly the smallest church in the world floats in the middle of a pond.

This rare symbol of Eastern philosophy in the West has been created over years of painstaking construction by the local community.

Part modern art project, part traditional chapel, this see-through church is only substantial from the right angle.

A collection of housewares from recent Irish history adjoined by a tower from ancient Irish history.

This ancient Irish religious site is covered in ancient carvings, many of which have barely aged.

A Romanesque tower appears when water levels drop.

Bell tower juts out from a village buried under a lake.

Immortalized by artists, this church incorporates a medieval lighthouse into its shoreside structure.

An ancient church on a tiny island covered in stone bible stories has controversially been turned into a museum.

This church in Pittsburgh is home to the largest collection of religious relics in North America.

The remains of an idyllic small town built for the film 'Big Fish' still stand around a rundown main street.

The only Bahá'í house of worship in North America and one of only a handful worldwide.

St Bernard de Clairvaux Episcopal Church, better known as one of the oldest European buildings in the Western Hemisphere.

A vision of beautiful Hindu architecture in the middle of the American South.

Wedding chapel's mysterious spiral staircase said to be miraculously constructed.

This popular pilgrimage site offers a hole filled with holy healing dirt.

The liveliest ghost town in the state.