This irregularly shaped sea fortress has defended not one but three different sovereign states.

The former home of Norway's greatest romantic composer.

Constructed on the ruins of a convent, this tower saved countless lives.

The most decorated dog of World War I is preserved in the Smithsonian.

It's home to the taxidermy remains of Peter, the dog who helped convict a murderer.

This seemingly out-of-place gas station by the Watergate hotel was once described as the most expensive gas station in the world.

A portal into the bricked up canal that runs through the heart of Washington D.C.

The word "Watergate" will forever be associated with the infamous scandal in 1972, but this fountain is famous in its own right.

An empty relic of the Moscow Olympics crumbles away in Estonia's capital.

A former major munitions plant that has been converted into a sprawling art space.

The narrowest house in America is seven feet of pure spite.

Long buried under the 20th-century landscape, this lift lock of the Alexandria Canal is the lone remnant of an ambitious early American transportation project.

These official units of measurement—including chains and perches—lie hidden beneath tourists' feet in a popular London hub.

A stargazing sculpture made from the ruins of an iconic telescope.

What do we know about the real woman behind one of the Beatles' most famous songs?

This abstract sculpture was initially so disliked that it got moved to the outskirts of town a few months after installation.

One of three sites in England that house the National Collection of Arms and Armour.

The former home of Victoria's first Lieutenant-Governor.

This fort dates back to 1588 and was colonized by the Portuguese, Dutch, and English and sits prominently on the Indian Ocean where azure water lap the coast.

This sculpture commemorates a naturalist and an illustrator whose work was a forerunner to modern field guides.

This small seaside reserve supposedly inspired a young Errol Flynn to take the nautical adventures that would define him on and off the silver screen.

A remarkable feat of Victorian engineering across the Firth of Forth.

A total of 14 men held the title of "president" before George Washington—their historical legacies are enshrined in the lobby of a hotel.

This small pedestal marks the spot of the first lot of land sold in Alexandria, Virginia in 1749.