A tiny Greek Orthodox church from the Ottoman era hides on a busy city street.

This small chapel holds the mummified heart of one of the heroes of the Greek Revolution.

This once architecturally advanced housing complex is now a haven for squatters that still bears the scars of war.

An often overlooked ancient site in downtown Athens with substantial history (and nature).

These caves secretly held national treasures during World War II.

Preserved portions of Athens's ancient defenses are on display in a subterranean parking garage.

A Byzantine church containing the holy remnants of three saints sits atop the site of an ancient temple.

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

There are many Byzantine-era churches still standing in Athens, but this is the only one with a 2,500-year-old column rising through its roof.

This historic structure has been used as a mosque, a barracks, a prison, a school, and a bakery.

This small museum once served as a royal hunting pavilion for King Otto Friedrich Ludwig.

A crushed gate and giant bronze head serve as a reminder of Greece's fight for freedom.

This graffitied 19th-century building was a prototype of European industrial architecture.

A preserved portion of an ancient Athens barrier is displayed in a hotel basement.

The oldest standing Byzantine church in Athens is tucked within a monastery in the middle of an upscale shopping district.

A Byzantine-era church hidden in a wooded area below the Acropolis.

This gem is often wrongly overshadowed by the larger, newer Metropolis church in Athens.

Where commuters walk through remnants of an ancient Greek necropolis.

Legend says this sacred tree was a gift from goddess Athena.

The ruined doorway is a portal to the building's turbulent and torturous past.

Large collection from the 3rd millennium BCE.

Heralded as the world's first theater, these ruins are often overlooked as they reside in the shadows of the Acropolis.

The ruins of an ancient Roman tomb hidden in the basement of a trendy clothing store.

A sharp sculpture made of thousands of pieces of jagged glass.