The remains of the great moral philosopher reside in a university in London.

The commemorative stone column conceals a secret laboratory.

This sprawling, Brutalist estate feels like a city within a city.

The ruins of a once-mighty medieval palace are hidden away in otherwise modern London

This column celebrates Rome's victory over the Goths, and may be the oldest Roman monument in Istanbul.

Byzantine emperors ruled, lived, and died in this 13th-century palace-turned-museum.

This historic hotel preserves many treasures from its heyday hosting passengers on the Orient Express.

Ancient serpentine sacrifice holder that has stood the test of time.

A fountain standing as a testament to a doomed alliance.

This museum was invented in a novel before being made real by the author.

This half-forgotten fortress was constructed by the Ottoman conqueror of Constantinople.

Climb a steep hill in 90 seconds on the second-oldest urban subway in the world.

The most metal church of all time was built in record time because of an international, pious pissing contest.

This remarkably well-preserved Egyptian plinth is pretty well traveled for a giant piece of stone.

A marvel of Byzantine engineering under the streets of Istanbul.

A subterranean necropolis blending Egyptian, Hellenic, and Roman traditions and art styles.

An unexpected treasure trove of military oddities, Turkish interior design, and North Korean art.

The ancient village known as Set Maat, or the 'Place of Truth,' located on this site served as a hub for intellectual and artistic endeavors.

This fortress was built using the last surviving stones from the Lighthouse of Alexandria, one of the Seven Wonders of the Ancient World.

The medieval center of the Islamic world was also once the seat of Saladin's sultanate.

Standing atop 2nd-century Roman ruins, this church is one of the oldest and most iconic in Old Cairo.

This ancient structure is widely thought to be the oldest intact pyramid in the world.

These Egyptian statues have survived for 3,400 years and were an acoustic wonder of the ancient world.

An ancient instrument used to measure the waters of the Nile so Egyptian farmers would know whether to expect famine or flood.