An homage to the medieval rulers of Bulgaria.

A gigantic statue of a Russian soldier watches over the ancient city of Plovdiv, a prominent reminder of the Soviet period in Bulgaria.

This ancient theater, restored in the 20th century, lives on as a venue for dramatic and musical performances.

This quirky UFO-shaped curiosity is often mistaken for the airport’s control tower.

Disney's abandoned animal island is now an overgrown ruin that was almost the coolest attraction ever.

Electrical pylon in the shape of Disney's beloved mouse.

A building so large that it has its own weather.

This Florida sinkhole hides a rainforest-like micro-environment in its depths.

A museum in England’s Lake District dedicated to the trusty pencil wants you to know the story of their World War II spy pencils.

Also known as "Robin Hood's tree," this tree became a famed location along Hadrian's Wall before it was cut down in an act of vandalism.

One of the last doorless, continuously moving elevators still in use in the U.K.

Museum celebrating the history of computers, especially their role in codebreaking.

The National Railway Museum in York is the largest railway museum in the world, attracting almost 1 million visitors per year.

A hundred copies of Antony Gormley's naked body stare out across the water.

Its collection includes a broad array of social, geographic, graphic design, and political history.

The commemorative stone column conceals a secret laboratory.

One of the few standing Roman lighthouses and a labyrinth of tunnels are a couple of the secrets at this historic castle.

This one has sailed five times as far as Sir Francis Drake's famous ship.

The largest oak in England is said to have been the hideout of Robin Hood and his Merry Men.

Ship-sized kinetic sculptural fantasy.

The sculpture is made of more than 100,000 knives collected to raise awareness about violence.

The watery entrance for condemned prisoners heading to the Tower of London is still visible along the Thames.

Stonehenge has nothing on Castlerigg’s views.

This unique bridge curls up like a caterpillar to let boats pass and then unfurls again to span a small canal.