More sculpture than building, this architecturally significant temple was built on the spot of Saint Peter's crucifixion.

This is the oldest Roman-made bridge in the city still existing in its original state.

The ancient latrines of the Greeks, in all their public glory.

1513 Turkish world map, full of European state secrets and snarky commentary.

This windmill has been grinding pigments for traditional paints for more than 200 years.

A comprehensive look at the art of Joaquín Sorolla in his former home in Madrid.

This unassuming bookstore in the heart of Madrid is one of the oldest in Spain.

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

View the ancient remains of buildings and the ancient "River of Hades" before hopping on a train.

These caves secretly held national treasures during World War II.

This striking sculpture of Icarus honors Greece's fallen flyers.

A sharp sculpture made of thousands of pieces of jagged glass.

The Cycladic architecture makes this Athens neighborhood feel like an island paradise hidden in the shadow of the Acropolis.

The railway carts travelers to central Athens's highest peak, which offers stunning vistas of the city.

This ancient Greek place of assembly and marketplace is being revealed layer by layer below the modern Athens cityscape.

This curious, round temple is the oldest still-standing marble building in Rome.

Installed in an act of one-upsmanship, the annual sundial in this church is also a symbolic victory for the Gregorian calendar.

A Nesting Doll of Churches.

The last moments of the ill-fated Pompeiians, frozen forever in plaster.

Pompeii's less famous neighbor is still revealing her secrets.

Jesus' footprints and the first catacombs in the world.

This community on a small Venetian island has taken to painting their houses in bright neon hues.

A vista of the city and sea from atop the little-known viewing deck on an unassuming Columbus statue.

The iconic boulevard is the perfect place to catch sight of a bicycling skeleton, a levitating Satan, or a chef with his head stuck in a pizza.