An Art Nouveau gem hides beneath the layers of city grime obscuring this once-magnificent building.

Legend says if you stick your thumb in the hole and it gets wet your wish will be granted.

1513 Turkish world map, full of European state secrets and snarky commentary.

A small etching on the white marble parapet was written in runic script by a Viking mercenary.

The ruins of this ancient fortification wall sit in the middle of a quiet, residential intersection.

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

Where commuters walk through remnants of an ancient Greek necropolis.

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

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

This small 16th-century church in Athens is almost entirely surrounded by a modern building.

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

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

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

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

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

Five sultans and their families rest in eternal splendor, teeming with overlooked beauty and drama.

Ornate, dome-topped cenotaphs fill this royal crematorium.

The beautiful 16th-century stepwell lies in the shadow of a famous fortress.

Sacred Indian temple that’s all monkey business.

More than half of this Indian palace is drowned but it looks all the more spectacular for it.

Also known as the "Red Taj Mahal."

This small cafe aims to empower acid attack victims and stop violence against women in India.

This picturesque horseshoe weir was first built in the 1600s to prevent flooding in the town of Bath.

An impressive armored bronze effigy marks the tomb of one of the medieval era's greatest warriors.