This Gallo-Roman sanctuary is dedicated to Serápis, god of the underworld.

A life-sized imperial army, buried in battle formation, has stood underground for over 2,000 years—built not for war, but for eternity.

These 400-year-old ruins are all that's left of the monastery where Ines de Castro was assassinated by the King of Portugal.

One of the largest Roman settlements in Portugal.

This crumbling Portuguese ruin overlooks the populace it once ruled.

A neolithic tomb converted into a tiny chapel.

A 16th century chapel decorated with bones, skulls, and entire bodies hanging from the wall.

The medieval castle built as headquarters for the Pope's secretive Knights Templar.

Perhaps the most spectacular grotto along the Algarve coastline.

The interior of the Overlook Hotel in "The Shining" was based on this Yosemite original.

America's most famous piece of self-built architecture.

Under the right circumstances, this waterfall in Yosemite briefly turns a luminescent fiery orange.

A living time capsule of the 1960s Richardson Bay water-front.

The 28-foot granite map plots the locations of 40 theaters in New York City.

This lavish room in a New York City mansion is a rare relic from the end of the Gilded Age.

Amid the marketing blitz of modern Times Square is an elegant holdover from its showbiz glory days.

A pedestrian island in the middle of world-famous Times Square emits a strange (and purposeful) humming noise.

Ride the subways of yesteryear.

What was once a vast naval cemetery is now home to nesting birds and pollinating bees.

A decommissioned military complex that's now a modern industrial park.

Once thought to be the fabled Holy Grail, it is now known to be an oil lamp.

Two large-scale sculptures of Adam and Eve greet visitors in the nude at the Time Warner Center in NYC.

Though its celestial ceiling is impressive, the true star is the vast collection of French books.

Mysterious 500-year-old tapestries depict a unicorn hunt.