On rare days, this abandoned castle's gatekeepers open its doors, revealing the eye-popping splendor hidden inside.

Its look is severe, but its location, isolated on a hill in the middle of the countryside, is particularly scenic.

The designer of this railway tunnel added a birthday present for himself.

The remains of the last Bosnian fortress to fall to the Ottomans are still standing.

The shell of a medieval fortress offers commanding views of the area it once protected.

This ruined fortress was the stronghold for a persecuted medieval leader and his infamous Assassins.

It's believed King John of England stayed at this 13th-century castle before riding off to sign the Magna Carta.

This cluster of little wooden huts once ground local farmers’ wheat into flour during the days of the Austro-Hungarian Empire.

A 6th-century stone lies at the site of the mythical battle waged between King Arthur and his nemesis Mordred.

Cornish legend says these ancient circles were people turned to stone for playing hurling on a Sunday.

Now nearly dry, this lake is said to be the ancient home of the Lady of the Lake, and was once thought to be bottomless.

Sometimes an island, sometimes a rocky outcropping connected to the world by a tiny suspension bridge.

400-year-old garden, restored to beauty.

The ruins of an 11th-century Norman castle with a rare, perfectly circular shape.

This ruined 15th-century hermitage is steeped in myth and mystery.

The largest greenhouse in the world is home to over one million types of plants.

A small, but award-winning beach known for its literally spotless reputation.

This little slice of old Jerusalem in Oklahoma is the evolution of a 90 year old passion play.

Yup, that's a 330-foot yacht passing over the highway.

Southern Ocean waters and glacial forces transform the Antarctic ice into these stunning bridges and caves.

Natural time capsule containing an alien ecosystem.

These giant volcano sponges in Antarctica are thought to be the world's oldest living animal, at 15,000 years old.

The bodies of some early polar pioneers are still buried beneath the harsh snows of the Antarctic.

Considered the most remote point in the entire world.