A completely underwater art museum sends a stark message about humans' impact on the environment.

Among the oldest structures in Madrid, these Moorish walls once guarded the medieval city of Mayrit.

A rare set of strings by famed instrument maker Antonio Stradivarius is on display in the Royal Palace.

Europe's first floating restaurant is home to a hilarious legend.

A floating cat sanctuary on an Amsterdam canal.

One of Amsterdam's narrowest houses is located right across the canal from its widest.

A king's bloodstained shirt is among the gruesome collection of artifacts displayed below Stockholm's Royal Palace.

Hanging within this medieval church are the bones of a beast allegedly slain by a fourth-century saint.

The small peaceful island off the Venice tourist circuit is where the city began more than 1,500 years ago.

Stare out over the lagoon and beyond from this 10th-century campanile on the island where the city of Venice began.

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

An ancient necropolis of magnificent tombs.

The ancient mosaics here are considered among the finest in the world, and serve as a stunning record of Greco-Roman daily life.

Beneath an ancient wishing tree lies an underground chapel with 12th-century frescoes and catacombs dedicated to a lady saint.