A Roman monument to their own civil engineering prowess.

A village on the east coast of England that has almost completely eroded into the North Sea.

The ruins of an ancient island city built atop a coral reef in the South Pacific are spectacular and strange enough to have inspired H.P. Lovecraft.

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

Surreal riveted sea forts once protected the Kent shores from German attack.

Once the most densely populated place in the world, this island is now a ghost town.

Hoax, mistake, or evidence of dinosaurs in human times?

An abandoned facility that has become a place of ritualistic satanic worship, or so rumor has it.

Ruins of a German Castle on top of a towering stone pillar.

The remains of what was, not so long ago, the world's largest city.

A battle between nature and architecture in the Cambodian jungle.

Super-heavy Nazi architectural experiment.

One of Scotland's most important modern structures, it just made the '100 Most Endangered Sites' list.

Every equinox this Maya pyramid puts on a spooky ancient light show.

Steam engines and conveyor belts are remnants of a genius system left in the middle of the Maine woods.

A walk through the historic city center, under the streets of Seattle.

An enormous concrete structure built over a nuclear crater.

The ghost town left by the worst nuclear disaster of all time is being taken over by nature and urban explorers.

Between Neo-Pagans and Neo-Nazis, these strange rock formations have a curious cult following and a very strange history.

The largest earthwork effigy in the world.

The inspiration for H.P. Lovecraft's horror stories and Batman's Arkham Asylum is now a condominium complex.

Northern Ireland's Brobdingnagian stepping stones.

The remnants of an early American attempt at missile defense.

The largest hewn stone in history.