The marker offers a rare chance to be in four U.S. states at once, though there's some controversy over its geographic accuracy.

An extravagant western hotel where every floor is the "ground floor."

This monumental Jesus is often referred to as "Our Milk Carton With Arms."

This haunted hotel built on natural springs once served as a hospital for a quack doctor promising a cure for cancer.

On the Spree bank, discover one of the last reminders of a symbolic wall that divided, and was torn down by the people.

Thousands of coffin-like pillars make up this controversial Holocaust memorial.

The bunker where Hitler took his own life is hidden under this deliberately ordinary parking lot.

A display of magnificent stained glass windows is the first exhibit of its kind.

The twin towers in this Chicago fountain use 50 foot tall video screens to spit on people.

A Bibliophile's Dream.

Four glass boxes hover over 1,000 feet in the air to give visitors an unparalleled view of Chicago.

This shop for all your super spy needs hides an educational secret.

Six ravens are kept captive (but well-fed) at the Tower of London to prevent the fall of the Crown.

Richard III supposedly disposed of his nephews' bodies here in an effort to seal his claim to the throne.

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

More than 5,000 artifacts donated by the people of the city, plus a room entirely devoted to the band U2.

The mummified heart of a saint lives on in this church—after a brief hiatus when it was stolen.

A museum that cashes in on its infamous little people while teaching you a thing or two about the Irish fey.

One of Ireland's most infamous prisons for rebels including men, women and children.

The gorgeous library at Trinity College is home to remarkable treasures of Irish identity.

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

Remnants of the 16th-century defensive wall still stand unassumingly within Edinburgh.

The taxidermy remains of the first mammal ever cloned from an adult cell are on display in Edinburgh.

A six-ton wedding present for the King of the Scots.