An artificial crater field that trained astronauts for lunar exploration.

The world's largest military aircraft cemetery.

Some 2,000 carvings show this rare desert spring has been an oasis for travelers for over a thousand years.

A network of concealed passageways lies within a busy London Underground station.

An alleyway plaque is all that remains of the independent Texas' envoy that forgot to pay their rent for over a century.

The signs of a long buried road can still be found hidden beneath a London sewer grate.

A 1,215-foot tunnel transports pedestrians beneath the River Thames.

A subterranean ice warehouse that has lain hidden beneath central London for over a century is now open to the public.

Hidden beneath the streets of London is a secret subway that only carried mail.

An old World War II hangar holds 20 vintage aircraft and the rare opportunity to take a ride in a 1940s warbird.

The largest wooden building in the world now houses a fascinating collection of aircraft.

Home of Howard Hughes' Spruce Goose.

The wooden airship was the largest flying boat ever built.

Portland had a unique approach to Cold War-era protections.

This historic steamboat is scuttled just a few hundred feet from where it was built over a hundred years ago.

World's only nuclear reactor operated by liberal arts undergraduates.

Where Nor'easters go to die.

A tourist attraction founded around a slumping cabin.

This stoic, if derpy, giant stands as a monument to Oregon's statehood and the novelty culture of yesteryear.

A collection of colorful dinosaurs hidden in an actual rainforest.

100-year-old shipwreck you can walk up to at low tide.

This concrete monster of a wreck lies in the mouth of Langstone Harbour as a monument to the incredible history of D-Day.

The remains of a Canadian train crash are now mouldering beneath layers of rust and graffiti.

An abandoned Victorian-era amusement park is rusting away amidst luxury houses.