The stately remains of Llywelyn the Great's mighty fortress.

This well-preserved Cistercian Abbey in a romantic pastoral setting has inspired artists like the poet Wordsworth.

Twenty-seven massive radio antennas on the high plains of New Mexico search for life on other planets.

These ruins of a pre-Columbian cliff village are among the most beautiful and well preserved in New Mexico.

Explore the largest pure gypsum deposit in the world, and go dune sledding while you're at it.

It appears as if a man is standing behind this giant airport clock, painting the hands in real time.

A Dutch clog company in the town of Zaandam loves the wooden shoes so much it made a museum for them.

An Amsterdam street lined with antique shops each one dedicated to a different obscure collection.

The attic of a four-century-old canal house hides a clandestine church.

Behemoth, cannon-like telescope operated by generations of Irish earls.

The world's tallest box hedge is found in a delightful garden.

Mysterious meeting place for UFO hunters near Area 51.

An eatery for UFO seekers on the Extraterrestrial Highway.

This medieval castle overlooking the Elzbach river looks just like it did hundreds of years ago.

Near the former site of numerous witch burnings, this lavish Edinburgh mainstay pays homage to Scotland's brutal history.

Overlooked by many, the two famous Scottish warriors guard the main gate of Edinburgh Castle.

This 17th-century street hidden beneath Edinburgh was once a breeding ground for the black death.

A rare wooden coffin set vertically into the Gothic arch of an ruined church.

Horrifically creative torture devices and shame punishments line the walls of this chilling museum.

A church of bones, decorated with 40,000 human skeletons.

Two stunning 17th-century libraries and a cabinet of curiosities.

Increasingly decayed figures stand as a powerful reminder of the human costs of Czech Communism.

Around 100,000 bodies are buried below the medieval headstones, many of which mark graves with multiple bodies stacked up to 12 deep.

The hidden lair of an alchemist rediscovered in a 2002 flood.