The geographical center of Budapest is marked with a 10-foot-tall stylized zero.

Model Trains and Much More in Hamburg.

Thousands of tourists and residents in Cologne affix "love padlocks" on the Hohenzollernbrücke Bridge to symbolize their affections.

Cold war icon and onetime "hole" in the iron curtain.

A restaurant and observation deck built in a unique broadcasting antenna.

A striking 12th-century-style castle built on the edge of a cliff.

Thousands of coffin-like pillars make up this controversial Holocaust memorial.

The fairy tale castle of the "fairy-tale king."

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

Mountain where Jesus was first tempted by the Devil.

These secluded and abandoned anti-aircraft defenses have become one the most scenic viewpoints in Barcelona.

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

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

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

This colorful statue welcomes visitors to a Barcelona park.

This fairy-tale castle would make Dracula (who is said to have been imprisoned there) jealous.

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