An ancient necropolis of magnificent tombs.

The ancient mosaics here are considered among the finest in the world, and serve as a stunning record of Greco-Roman daily life.

The only ancient site that remains on the south bank of the sacred Ilissos river.

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

Where commuters walk through remnants of an ancient Greek necropolis.

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

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.

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

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.

This mystical orb covered in strange symbols is thought to have been used in ancient Greek magical rituals.

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

A 2,000-year-old computer demonstrates remarkable engineering and astronomical precision.

The hallucinogenic center of the ancient world.

A tribute to an iconic act of defiance from the Croatian War of Independence involving a small car.

Gargoyle head that brings good luck.

The complex has been abandoned since the Croatian War of Independence, barring a stint as a set for 'Game of Thrones.'

Ride in 1960s style on the private luxury train Marshal Josip Tito used to travel around Yugoslavia.

A pair of connected skyscrapers form this symbolic gateway.

Destroyed Serbian army headquarters sits half crumbled in a largely revitalized Belgrade.

A Red Cross memorial museum at the site of the Niš concentration camp that operated for four eventful years during World War II.

Structure built from the skulls of vanquished foes.

A pretty park of over 1,600 olive trees that grew from just three saplings brought over from Spain.