Abandoned castle was once a grand example of Russian privilege, built exclusively to win a frivolous bet between noblemen.

Native Americans built this circle of stones, which was used to predict astronomical events.

1920's mining camp and environmental education center is serving to protect the surrounding forest, one of the last of its kind in the Pacific Northwest.

An unrealized dream to wirelessly electrify the entire Earth.

The one-time watch house for incoming ships at the Golden Gate now stands abandoned and hidden in trees.

The intricate stonework of Machu Picchu serves as a testament to Incan engineers.

Red frames showcase remnants of one of New York's original subway stations.

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

Pompeii's less famous neighbor is still revealing her secrets.

This rugged area of red rocks and arches is often considered one of the most beautiful places on Earth.

One of the most accessible undersea plane wrecks in the world.

These Nubian pyramids are strange and unique, even by pyramid standards.

Wee (and not so wee) footprints that insects and reptiles of the Paleozoic Era left behind.

Egyptian Revival movie palace abandoned for decades and restored in 2013.

A Texas-sized particle collider that was abandoned due to its Texas-sized budget.

No telescopes, no power, no gift shop: The Observatory of Chichen Itza, one of the world's oldest observatories, takes astronomy back to basics.

Hauled from the water's depths, Henry VIII's flagship is preserved in this capsule-shaped museum.

A two thousand year old brothel uncovered in Northern Greece.

Celebrated as a center of civilization, the remains of the ancient city have been nearly destroyed by greed, egoism, and war.

Rock-hewn monastery complex with hundreds of cave structures tucked away into the mountainside.

The largest prehistoric ruins south of the Sahara, once a powerful center of international trade.

The hallucinogenic center of the ancient world.

Preserved Inca city and site of the last Inca stronghold against the Spanish conquistadors.

Retirement home for giant obsolete machines.