The castle still holds traces of the abandoned Roman fort it was built atop.

Stroll through Welsh history in a village of reconstructed structures.

It houses the remains of a 17th-century version of the Titanic.

A stunning architectural yet functional feat, towering over Oslo.

An abstract monument to a symphonic composer.

Walk along the medieval fortifications that have been protecting Tallinn since the 14th century.

During the Soviet era, the spire of this longstanding church was used as a radio transmission tower.

A monument to the three wars that led to German unification towers within a Berlin traffic circle.

A narrow passage next to a cafe leads to a courtyard exploding with murals, tags, and paste-ups.

This Moorish fortress has guarded Málaga from the slopes of Gibralfaro hill for nearly a thousand years.

Amsterdam's narrowest house facade is a monument to 17th-century tax evasion.

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

This city square is home to Amsterdam's oldest church and a statue honoring Dutch sex workers.

You can spot this teeny tiny stained-glass window from the Bonifacius bridge.

The Argonaute submarine was the French navy's pride and joy in the 1950's.

Montmartre's sole surviving windmill became an iconic landmark for 19th-century painters, artists, and bohemians.

This statue was given to France by the United States to commemorate the centennial of the French Revolution.

Twelve grave-faced marble angels guard the emperor's tomb at Les Invalides.

This bridge was constructed from the rubble of the infamous Bastille.

This demon atop the Notre-Dame de Paris looks utterly bored.

These were the largest wind chimes in the world when artist Tom Van Sant created them for a California mall in 1967.

A Looff creation in Santa Monica best described as “a California-Byzantine-Moorish-style fantasy.”

French prisoners carved these boats from the bones of their meat rations.

Opened as part of the New Deal, the training facility now features World War II-era structures and a pylon that once stood at the World Trade Center.