One of the best collections of Byzantine art housed in a magnificent, 19th-century neoclassical home.

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

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 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.

An ancient site that has revealed incredible artifacts including portions of the Themistoclean Wall.

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

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

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

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

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

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

Gladiators once walked this ancient, subterranean passage.

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

An ancient Greek monument and a Byzantine church coexist inside this cave.

The Cycladic architecture makes this Athens neighborhood feel like an island paradise hidden in the shadow of the Acropolis.

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

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

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

A micronation on an islet along the coast of a Portuguese island.

Men in rubber-soled boots serve as your "brakes" on this toboggan ride Hemingway described as "exhilarating."

A lush oasis full of vibrant plants and striking geometric displays.

This ingenious engineering solution was built to stop the "theft" of canal water.

A great example of the inventive canal bridges that were deliberately split down the middle.