One of the largest underground systems runs under Canada's largest urban center.

One of the Seven Wonders of the Modern World holds the world's tallest metal staircase.

Replicas of Apollo's leonine stone guard cats still line a sacred row in Greece.

A Bronze age settlement on the Greek island of Santorini might have been the inspiration for Plato's Atlantis.

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

Giant marble phalluses on the sacred island of antiquity.

Inside a former cabaret, seven floors of erotic art.

The celebrated eyesore created by starry-eyed sweethearts.

This demon atop the Notre-Dame de Paris looks utterly bored.

Twelve grave-faced marble angels guard the emperor's tomb at Les Invalides.

An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.

High atop the Eiffel Tower is a small apartment built exclusively to entertain the science elite and make the rest of Paris jealous.

The vast, legendary catacombs hold secrets much stranger than stacked bones.

The world's second largest single-dish radio telescope, once used to contact E.T.

This staircase in a lush tropical grotto was built by enslaved laborers and renamed to honor Queen Victoria's role in ending slavery in the British Empire.

Once featuring over 60 miniature replicas of famous Chinese locations, the Splendid China theme park was completely abandoned and is now mostly rubble.

Electrical pylon in the shape of Disney's beloved mouse.

Visit these gentle, bell-bottomed, exquisite equines at the home of North America's first Gypsy Vanner horses.

Recycled junk and fishing buoys litter the yard and facade of this bait shop cum art project.

Island ghost town detailing Flagler's folly in building the Overseas Railroad.

This spiny beast guards an artist's village while vying for the title of largest lobster in the world.

The first custom-designed building to showcase the works of Dale Chihuly is a wonderland of glass and light.

An icon among Florida's pre-Disney tourist attractions.

The culprit who accidentally lit this 3,500-year-old tree on fire stated "I can't believe I burned down a tree older than Jesus."