A popular legend claims that the famous pizza was invented at a restaurant in this alley.

A labyrinth of ancient tunnels hidden below the city holds the ruins of 2,500 years of history.

This post-Ottoman era church in Athens was built by locals to serve the residents of Anafiotica

Gladiators once walked this ancient, subterranean passage.

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

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

The picturesque birthplace of Icelandic democracy is drenched in the blood of its brutal past.

Three columns of volcanic rock shoot out of the ocean.

This natural Icelandic fissure allows divers to swim right between two volatile tectonic plates.

This valley of hot springs and boiling mud pots is home to the record-holding "Geysir," which originated the English word.

If a glacial river suddenly diving into a sheer chasm via a dramatic, multi-stage waterfall isn't peak Iceland, it's certainly close.

Walk in the footsteps of the gods and straddle two tectonic plates.

This fantastical waterfall is hidden in a cave located in a cracked cliff.

Iceland's largest lagoon is home to stunning multi-colored icebergs.

One of the tallest buildings in Iceland, and perhaps, the most visually impressive.

America's only nuclear missile silo open to the public.

Paranormal investigators claim this abandoned asylum is the most haunted spot in the eastern U.S.

An Irish Memorial commemorating those who perished due to potato blight.

A tour de force of a fountain, memorializing a man who loved fountains more than anything else.

This elaborate towering structure was once famed for its revolutionary height.

Yo, Adrian!

An abandoned stretch of highway, deteriorating next to the operational one.