A marvel of Byzantine engineering under the streets of Istanbul.

What once sat in the world’s spotlight is today a largely disused ghost complex.

Where commuters walk through remnants of an ancient Greek necropolis.

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

This legendary city has been a tourist attraction for centuries.

A minotaur, a labyrinth, and a dubious restoration pull in visitors from around the world.

The hallucinogenic center of the ancient world.

The Netherlands' first car tunnel has an unusually rectangular shape.

A massive explosion that leveled hundreds of buildings in the city of Leiden is remembered by a waterside plaque.

An ancient Egyptian temple sits within a modern European museum.

Now a museum, this building was once a 14th-century monastery and the place where the founder of the Dutch nation lived and was assassinated.

Building Men of War and Indiamen from Holland's Golden Age.

Rotterdammers' dirty minds gave this santa a dirty nickname and cursed it to a life of wandering.

Wind power station for making famous Ketel One vodka.

This giant wire frame man sculpture is crouched in contemplation.

Amsterdam's former hotspot for public executions and dissections.

This historic Dutch newspaper building is covered with media-themed details—and one unrelated oddity.

This enormous storm barrier is one of the largest moving structures on Earth, with each arm taller than the Washington Monument.

Scale model of St. Peter's Cathedral (Rome) in the middle of a small Dutch town.

A trio of red, white, and blue stones embedded in the streets of Leiden are markers of medieval territory and law.

'The Letters of Utrecht' lays out a ribbon of poetry one letter at a time, with no final verse in sight.

A statue of the second-tallest Dutchman in history.

The birthplace of most all of Europe's space missions is here on the Dutch coast.

Built by crowdsourcing, this wooden foot bridge saved a part of Rotterdam that was languishing in wait of city funding.