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

A marvel of Byzantine engineering under the streets of Istanbul.

This memorial commemorating fallen Swiss Guards of the French Revolution has been called the saddest stone in the world.

Macabre astrological automaton clock dating to the late 1400s.

Ruined 11th century abbey built by King David I in Edinburgh, Scotland.

The oldest public library in Ireland.

A remarkably intact castle that once was the largest in Ireland.

When you're a great Russian Tsar, even your vomit gets a statue.

A 125-meter long "tribute to the Brazilian people."

The design of the Palacio Salvo has been described as "a lighthouse on top of a building."

A bright little alley in La Boca is a part of tango history.

Buenos Aires' city of the dead contains some very famous remains, including Eva Perón.

A beautiful deserted greenhouse in the middle of a park.

A sculpture of a giant hand reaches for the stars in the middle of the Atacama desert.

This Japanese-inspired labyrinth of hot springs is hidden in a Chilean forest.

The largest stone moai on Rapa Nui.

This odd Chilean waterfall-cano hotel must be entered via a rope bridge.

Mother Nature outdoes herself with this stunningly beautiful set of caves carved into marble.

Preserved Inca city and site of the last Inca stronghold against the Spanish conquistadors.

The intricate stonework of Machu Picchu serves as a testament to Incan engineers.

At Monet's beloved home you can still see the Japanese bridge, waterlilies, and weeping willows that were the subjects of some of his most iconic paintings.

The bright red stripes streaking across the rocks are the star feature at this Icelandic waterfall.

The oldest (maybe) swimming pool in Iceland is a stunning oasis built into the side of a lush hill.

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