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

This Transylvanian church has changed its denomination four times.

This hauntingly beautiful cemetery outside a medieval citadel is full of winding paths and ivy-covered graves.

Eighty million natural history specimens call this gargantuan museum home.

One of the most photographed buildings in a city known for its Modernista architecture is an abandoned squat.

Gaudí's famously flamboyant architectural style is on full display in this sprawling park and garden.

An unusual stroll through gentlemen's erotica demonstrates that pornography is timeless.

A stately palace has been converted into the world's largest cannabis museum.

One of Antoni Gaudí's most classic buildings is well-known for its "dragon-back" design.

An early 20th-century bullring converted into a modern shopping center.

This cemetery features modernist statues as strange as its name.

The vast, legendary catacombs hold secrets much stranger than stacked bones.

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

The European towns of Brașov and Râșnov each have proud signs reminiscent of the Hollywood sign.

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

This bone-filled cave got its name after they found 140 bear skeletons inside.

Twisted buildings adorn the banks of the Rhine river.

This futuristic German television spire is actually the world's largest digital clock.

This former steel and coal plant is now a neon-lit industrial fantasia.

Inspired by "The Starry Night" this Dutch bike path turns into a glowing work of art each night.

A giant portrait of an ancient king looms over the river.

Moss and stone turn this waterfall into an otherworldly liquid veil.

A collection of items from a way of life that no longer exists.

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