Nine centuries-old fortresses guard the walls of this medieval Romanian city.

A fire once nearly devoured this gorgeous 14th-century Gothic cathedral.

This snug medieval lane is one of the narrowest streets in the world.

The possible imprisonment of Vlad the Impaler here earned the medieval castle its nickname, "Dracula's Castle."

The ancient Greek Titan guards this massive dam holding a lightning bolt to symbolize electricity.

The legendary cliffside castle of three-time Voivode of Wallachia, Vlad the Impaler.

This massive underground salt mine now holds a sci-fi theme park in its depths.

This cliff-face port is considered a masterpiece of mining engineering.

On the coast of Sardinia, a once-great mining village is finding new life as a coastal resort town.

Mysterious tombstones thought to be remnants of Atlantis.

At an estimated 3,800 years old, this olive tree is one of the oldest on earth.

This bustling Italian plaza is built on the ruins of an ancient Roman amphitheater.

Fortified medieval tower house with lovely roof garden.

A copy of the famous statue can be found in this Florence piazza, along with one of the most breathtaking views of the city below.

This bronze boar's snout has been rubbed to a golden sheen by visitors seeking good fortune.

A star-shaped fortress town fort built in the geometric model of the Renaissance utopian city.

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

19th-century scientists would make the pilgrimage here to verify the precision of their measuring sticks.

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

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

The commemorative stone column conceals a secret laboratory.

A little slice of Japan and its aesthetics in London's Holland Park.

The beloved beast's taxidermy remains sit in the Natural History Museum's cafe.

Eighty million natural history specimens call this gargantuan museum home.