The ancient latrines of the Greeks, in all their public glory.

Climb a steep hill in 90 seconds on the second-oldest urban subway in the world.

Ancient serpentine sacrifice holder that has stood the test of time.

The alleged house of the Virgin Mary is tucked away in a park and nature preserve on Mt. Koressos in Turkey and is holy to both Catholics and Muslims alike.

This remarkably well-preserved Egyptian plinth is pretty well traveled for a giant piece of stone.

The deepest underground city in Turkey was designed to protect 20,000 people behind massive stone doors.

A marvel of Byzantine engineering under the streets of Istanbul.

In this historic region, homes and churches are carved into ancient volcanic rock formations.

This vast masterpiece of Moroccan architecture spreads across 20 acres.

Deliberately hidden for centuries, the magnificent Saadian Tombs were eventually uncovered in 1917.

Vast stretch of tide-pools with a unique Moroccan charm.

It took 40 years to build this Eden-like garden in Marrakech, later restored by Yves Saint-Laurent.

A natural swimming hole that was once a ceremonial center for Mayan priests.

Sparkling, calcite-covered skeletons of children who may have been sacrificed to appease an angry god.

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

This stunning concert hall has become a symbol of Iceland's national recovery.

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

A little-visited waterfall in an otherworldly landscape.

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

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

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

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

Medicinal spa created from the mineral-rich runoff of a geothermal power plant

An architect's childhood fantasy treehouse made real.