The now-abandoned tunnels were built for the transcontinental railroad on the route where the first wagon train entered California.

These ancient sunken lanes were naturally tunneled into the soft ground by countless footsteps.

This unique Renaissance castle was turned into a home for Nazi occultism.

The plague quarantine island home to the alleged "Vampire of Venice."

Shoreline strewn with the remains of ghostly fallen trees.

The oldest inn in England served brew to the crusaders.

An ancient Egyptian temple in the middle of Madrid, Spain.

A 14th century bridge built as a fortress, where the devil lurks on one of its towers.

A small town Romanian cemetery filled with darkly humorous gravestones.

Thirty creepy ghosts now inhabit this decaying 14th-century church.

Japanese gardens dedicated to the Japanese farmer that refused to throw in the trowel.

Virgil's many-mouthed gateway to the underworld.

An ancient city exhumed from the depths of the ocean.

This Virginia railway overpass is said to be haunted by a serial killer in a rabbit costume.

Buildings that dynamite couldn't bring down were abandoned because of bathroom issues.

This natural sea cave hides a small wonderland of natural turquoise beauty.

Ancient pueblos built into the base of a natural canyon wall.

The often-overlooked ruins of one of the first buildings designed by famous landscape architect Frederick Olmsted.

A suspended garden, now gone, once hung in the middle of this abandoned church.

Buried five stories underground, this Soviet bunker is packed with gas masks and Cold War paraphernalia.

One of the largest-ever mental hospitals now sits abandoned, surrounded by 25,000 unmarked graves.

A new sculpture calls attention to climate change in the centuries-old city it threatens.

Abandoned Japanese ghost town gives a glimpse into what our own metropolises may leave behind.

Fittingly, America's museum of architecture is itself a magnificently designed old building.