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

This abandoned stepwell is one of the largest, deepest, and certainly one of the creepiest in India.

A bronze monument to the infamous radio broadcast in the real New Jersey town where the fictional Martians crash-landed.

A fairytale Gothic castle steeped in Nazi treasure conspiracy theories.

This mysterious and once-grand memorial still embodies a remarkable architectural vision.

The hollow trunk of this 650-year-old tree was used as a hideout by two Jewish brothers during World War II.

Naturally formed rock city in Poland.

A striking public sculpture representing the period of martial law in Communist Poland.

In the midst of a living monument to Soviet social engineering, Polish Catholics built this church by hand.

Beneath Kraków Old Town's main square lies a hologram-filled medieval market vampire graveyard wonderland.

This uber-quaint Polish village is known for its habit of painting elaborate floral motifs on just about everything.

One of only two places in the world where two rivers cross each other without the waters mixing.

The oldest wind turbine in Europe, constructed by a group of friends in 1932.

A statue honors the children who fought Nazis in Poland.

A tribute to the Polish insurgents who fought in the failed attempt to end their city's Nazi occupation.

The 700-year-old fortress was the site of Count Orlok's castle in "Nosferatu."

The enchanting archway is the only surviving portal into Dublin's lost medieval wall.

The Grand Lodge of Ireland is one of the oldest in the world, full of fantastical, elaborately themed rooms.

Dublin's "Dead Zoo" serves as a window to Victorian museum design.

A sacred well steeped in Pagan roots on the West Coast of Ireland.

There might not be much left of these Irish ruins, but their linguistic legacy is still going strong.

The ancient tomb acts as a calendar that keeps perfect time.

Certain traditions prevail on the least-visited island of the Aran Islands.

A tiny microvalley etched into the side of Knocknarea Mountain hides another world.