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.

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

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

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

Scars of this building's past life as a violent prison still cover its walls.

One of the greatest collections of coins in the world is housed in the former mansion of an archeological pioneer.

The site where hundreds of Greeks were tortured by the Nazi secret police is now a cosmetics store.

This ancient hydrological marvel is now the base of a modern outdoor cinema.

The railway carts travelers to central Athens's highest peak, which offers stunning vistas of the city.

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

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

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

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

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

This building displays the scars of the “Dekemvriana,” a dark time in modern Greek history.

The home of Greece’s national poet sits crumbling in the middle of a popular tourist district.

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

These ancient ruins hide in plain sight next to a dessert shop.

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

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

These caves secretly held national treasures during World War II.

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

An ancient octagonal weather station named for the eight Greek gods of wind.

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