An eerie collection of the surviving structures from a past celebration of the future.

Its appearance in "Game of Thrones" may spur on the long-awaited restoration of this medieval shipyard.

Drink the 'Blood of Christ' in this Roman Catholic fever dream.

Machinery left over from California's once thriving mercury industry now attracts artists and explorers.

A deserted hodgepodge of experimental structures designed by nearby university students.

A Mysterious Masonic tomb in San Luis Obispo.

A 16th century chapel decorated with bones, skulls, and entire bodies hanging from the wall.

"Portugal's Stonehenge" is made up of nut-like stones aligned with the heavens.

An abandoned mine now resembles a post-apocalyptic landscape of derelict buildings and blood-red pools of water.

This small chapel is built of human bones and decorated with a golden skeleton.

This unassuming chapel in Portugal plays host to a ghoulish collection of bones.

Perhaps the most spectacular grotto along the Algarve coastline.

These 100-year-old tunnels in downtown Provo house artists, restaurants, and a few surprises.

An ancient and majestic fortress that played an integral role in Portugal's road to independence.

This eccentrically decorated palace is replete with grottoes, fountains, tunnels, and caves.

This memorial to a murdered empress took 20 years to design, then spent 30 years hidden away in storage.

The oldest private art gallery in all of Hungary.

A trail of iron footwear stands as a monument to the thousands executed along this riverbank during WWII.

A series of caves under Castle Hill that once held the prisoner Vlad Tepes, better known as Count Dracula.

Built in 1870 at the bridge that connected Buda and Pest, this spectacular incline railway was almost lost forever during World War II.

This almost-forgotten underground dungeon housed several convicts over the years, including Caravaggio.

The medieval home is still engraved with the symbol of the profession, an eye flanked by two axes.

This subterranean necropolis holds three floors of antler-dug grave caves.

This building has survived for more than a century and remains virtually untouched.