This hermitage spanning an Italian river gorge draws pilgrims hoping to heal ailments like arthritis and migraines.

A sprawling network of century-old subterranean catacombs lies beneath a nondescript suburban home.

A small etching on the white marble parapet was written in runic script by a Viking mercenary.

An otherworldly, fossil-rich cobble beach holds Viking graves, cairns, and other remains.

This 13th-century monastery chiseled into the side of a mountain is equipped with a bridge that can be lifted to protect against raids.

This former chapel resides on an island connected to the mainland by one of Shetland's iconic beachy tombolos.

A home built with marble tombstones from the graves of 2,200 Union soldiers buried in a Virginia cemetery.

Hidden in Central Park's Ramble is a troublesome cave buried just beneath the surface.

The Roman Emperor's lost summer home and grotto full of enormous sculptures sit along the Italian seashore.

This enormous sinkhole hides a secret world created from divine wrath.

A devilishly named gorge that was a sign of salvation for many pioneers.

Underneath downtown Lincoln resides a network of caves that was also the city's first brewery.

An imperial church bombed to ruins during WWII now stands as a jagged memorial.

This Viking-inspired miniature golf course features a pirate ship and views of Icelandic landscapes.

Inside this church is an obscure piece of art carved by the famous Alice Liddell.

The only thing sweeter than the potatoes is the canine proprietor of this roadside stall.

The doodles of a genius line the walls of a secret room under the Medici Chapel, where they were hidden for nearly 500 years.

This ancient amphitheater was restored in the early 1990s.

Walrus skulls and narwhal bones were found here while excavating a 900-year old church.

This hauntingly beautiful cemetery outside a medieval citadel is full of winding paths and ivy-covered graves.

Climbing to the top of the cathedral's bell tower offers sweeping views of these medieval ruins.

A Romanian church built from one single oak.

A fire once nearly devoured this gorgeous 14th-century Gothic cathedral.

This Romanian village may have been drowned, but it is long from forgotten.