The only subway station in the city that still makes use of gap fillers.

A commemorative plaque hides a door that leads down to the New York Public Library's underground book bunker.

A diminutive statue that was inspired by the sculptor's own daughter.

Spain's largest bullring offers a unique glimpse at architecture and history.

The final resting place of the great navigator, or maybe his brother.

The world's largest wooden structure.

A triumphant marble and bronze fountain depicting a 15th-century Hungarian king and his hunting party.

From cartoon characters to tiny tanks, a guerilla sculptor's little bronze statues are hidden throughout the city of Budapest.

This fortress dates back to the 6th century and is also the site of a controversial abandoned restoration project.

Chelsea's soldiers were given strict orders when crossing this historic bridge.

London's creepiest cemetery was once the site of dueling magicians and mobs of stake-carrying vampire hunters.

The only ancient site that remains on the south bank of the sacred Ilissos river.

These caves secretly held national treasures during World War II.

Legend says it was constructed with the destroyed pillar of an ancient Greek Temple.

The only surviving choragic monument is a trophy awarded in 334 BC for the winning dramatic chorus.

A man's head is enshrined beneath a statue near the first building constructed for the modern Olympic Games.

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

These engineering masterpieces are a dominant feature of the Belfast skyline.

During the heyday of fishing in Hastings, there were more than 100 of these storage facilities.

Preserved behind glass, the ruins of a medieval building used to store human remains.

A 2,000-year-old computer demonstrates remarkable engineering and astronomical precision.

An important example of architectural history slowly decays in the city center.

What might be the oldest living tree in London has survived fires, bombings, and estate agents.

This reconstructed Norman castle is the world's most accurate, from location to livestock.