This historic black and white monastery is one of Bulgaria's architectural jewels.

Bizarrely shaped rock formations in northwest Bulgaria come with equally bizarre legends.

An architectural marvel that spans the Arda River, and has stories of a haunted past.

An abandoned saucer-shaped monument in the Bulgarian mountains.

Looming communist pillar with a Czech twist.

The "lost friend” is the most famous of the six moai statues that were removed from Easter Island.

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

This Slovak bridge is known both for its connection to a national uprising and its UFO-shaped eatery.

This Slovakian statue of an emerging sewer worker might just be a bronze peeping tom.

A history of heat is on display at this unique Austrian museum.

This series of Baroque passageways in Vienna's cultural center mix old architecture with modern art.

Apartment complexes built into huge repurposed natural gas tanks.

Vienna's giant wonder wheel had a starring role in one of the greatest noir movies of all time.

Beautiful Austrian natural history museum with carved ceilings and row after row of ancient taxidermy.

The beautiful baroque library of the Hapsburg empire.

Berlin's natural history museum houses the world's largest mounted dinosaur and the late beloved polar bear Knut.

The most visited, and possibly most controversial, museum in Germany.

Construction of Barcelona's iconic (but controversial) church is expected to be completed in 2026—a century after the death of its architect.

Mountain where Jesus was first tempted by the Devil.

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

This cemetery features modernist statues as strange as its name.

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

A towering monument in Spain has proven to be more labor-intensive than initially planned.

A stone slab in Madrid marks the point from which the distances of Spain's national roads are measured.