While most wind tunnels test scale models, the "Cave of Winds" was large enough for actual airplanes.

The monument's pointy aluminum tip has been melted down by repeated lightning strikes.

Daredevil repair workers can worm their way out the access hatch, loop ropes over the apex and rappel down the monument.

Ruins from the Parthenon and petrified wood line the interior of one of the world's most famous monuments.

Look closely and you’ll notice that the color changes a third of the way up the tower.

A three-story tower of books about Abraham Lincoln is one of the more unusual monuments to the president.

Tucked away in the Tower of London is the weapon once used to execute high-profile prisoners.

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

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

Scattered throughout London are ancient remnants of the city's former bounding wall.

At almost 1,000 years old, this is the oldest known door in all of Britain.

The popularity of Sherlock Holmes led to the creation of his fictional address, turning the orderly London street numbers askew.

An enigmatic monument to the Irish revolutionary who plotted an uprising against British rule.

A statue in the center of Dublin dedicated to one of their favorite sons of rock & roll.

A mysterious plaque to the even more mysterious "Fr. Pat Noise," killed in "suspicious circumstances."

Some of the saint's blood and bones are said to reside in Dublin.

This supermarket offers shoppers a window into the past alongside their groceries.

The modern birthplace of Irish freedom.

Former wax museum from the 1960s, home to many wax U.S. Presidents and the famous White House miniature.

House of vintage taxidermy and Steampunk sculptures in a quiet Pittsburgh neighborhood.

The last street in Pittsburgh that's paved with wood.

The largest university building in the West is a gothic masterpiece containing dozens of theme rooms based on different countries.

This riverside restaurant delivers elegant dining in a historic 1901 train depot. 

There aren't too many operational funiculars around, but Pittsburgh has two!