A memorial commemorating the only Scottish police investigation into an extraterrestrial incident.

An anti-tank graveyard in the English countryside.

A long-abandoned relic of World War II.

This bunker in northern France was built by Nazi German forces with the intention of launching up to 50 V2 rockets at London each day.

These structures were inspired by both Native American shelters as well as, strangely, an ice cream shop.

A decomissioned facility where the German "Transrapid" maglev trains were once tested.

This museum is filled with an eclectic collection of unique inventions.

The largest man-made crater in the U.S. marks the spot where we once tested mining with nukes.

In the middle of an extremely unforgiving and desolate high desert is the most secret military facility in the world.

An eatery for UFO seekers on the Extraterrestrial Highway.

Mysterious meeting place for UFO hunters near Area 51.

The control tower at the historic weapons range is now available as a highly unusual vacation rental.

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

An engineering error ensured this cavernous 350-foot-long subterranean thoroughfare was never used as intended.

Perhaps the only prehistoric monument with its very own public bus stop.

Scotland's only funicular railway is also the United Kingdom's highest.

This abandoned gun tower was built to defend the River Thames from a French naval attack.

An abandoned World War II tank left to rust in the downland.

The scene of the United Kingdom's most famous UFO incident, dubbed the "British Roswell."

A working farm turned into a museum dedicated to the world's most unbelievably tiny cars.

Aliens and monsters lurk inside this museum dedicated to one man's lifelong adoration of all things sci-fi.

This East End pub gained notoriety as the site where gangster Ronnie Kray publicly shot a rival.

After the band included its number in one of their songs, the box became a monument to the musical group.

At night, the enormous sculpture looks like a UFO hovering above the English hills.