The famous sculptor had a hand in this imposing fortress.

"Holy Wisdom" overlooks the city that became its namesake.

A striking symbol of the Bulgarian capital.

A Bulgarian monument to Russia's role in World War II is constantly being painted in pop culture protest.

These abundant, over-the-top monuments are so widely scattered that they define the entire compact capital cityscape, often leading to jokes about whether there are more statues than residents.

Stockholm's decidedly unique public transit system has doubled as the world's longest art gallery for decades.

This collection of over 50 murals celebrates Brussels' rich history as the self-proclaimed home of the "comic strip."

One of the most photographed locations in the entire city.

This ancient theater, restored in the 20th century, lives on as a venue for dramatic and musical performances.

This striking sculpture of Icarus honors Greece's fallen flyers.

This black sand beach was crafted from volcanic explosions including the historic Minoan eruption.

The ruins of an ancient Roman tomb hidden in the basement of a trendy clothing store.

This ancient Greek place of assembly and marketplace is being revealed layer by layer below the modern Athens cityscape.

A little sculpture with a large wardrobe.

Legend says these colorful, invasive residents are the descendants of birds released by Jimi Hendrix.

After nearly 60 years, there's still a bear at Paddington Station looking for help.

A 1,215-foot tunnel transports pedestrians beneath the River Thames.

A student driver's nightmare.

Eighty million natural history specimens call this gargantuan museum home.

Originally meant to hold a statue of King William IV, this support sat empty for years. Today, it hosts a rotating cast of public artwork.

Once designed as the entrance to Buckingham Palace, this structure was later relocated and stands as a victory arch.

Catacombs turned marketplace.

Spitalfields' regal market goat is said to be a monument to the area's migrant population but most are pretty sure it's just a goat.

Now abandoned, the first public health hospital in the U.S. saw more than one million immigrants from around the world.