The largest Art Nouveau complex in the world is a Barcelona hospital with a 600-year-long history.

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.

Time stands still at this serene burial ground in the center of Budapest.

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

This park on the outskirts of Rome boasts two ancient Roman aqueducts and a medieval tower.

What appears to be an ancient Roman temple is actually a Catholic church.

A large replica of a monumental Roman inscription is located on the side of this museum.

The remains of this 2nd-century Roman temple are incorporated into a modern building.

These hut foundations are believed to be the residence of Romulus, founder of Rome.

Roman politician Herodes Atticus built this nymphaeum to honor his wife, whom he may have murdered.

The ruins of the largest gladiatorial school in Rome are largely hidden under modern streets.

This ancient market is often referred to as the oldest shopping mall in the world.

Stone memorial that's said to predict the death of the pope and the site of the Cadaver Synod.

A detailed pachyderm supports Rome's smallest Egyptian obelisk.

This large, circular tomb is the final resting place of the first emperor of Rome.

The best preserved Paleochristian basilica in Rome hides a number of oddities and secrets.

This ritzy Italian market is built around a statue of an unforgiven heretic who was burned for his belief in an endless universe.

This beautiful park on the outskirts of Rome protects the ruins of two colossal ancient aqueducts.

2300-year-old Roman road connecting the empire.

Hundreds of lucky felines haunt the ruins where Caesar was murdered.

This 6th-century church has the largest and best-preserved collection of Byzantine mosaics outside Constantinople.

An incredible mosaic-lined monument said to have held the remains of an ancient Roman empress.