Places Added by Mark Casey

A well-preserved network of cavernous tunnels have spent silent centuries removing Toronto's waste.

A humid oasis combines recreation with exploration in a unique underwater cavern.

A 2000-year-old Roman amphitheater lies just below Guildhall Yard.

Scattered throughout London are ancient remnants of the city's former bounding wall.

César Baldaccini's iconic sculpture of a 40-foot thumb stands tall in La Défense.

Fascination continues to surround one of history's most infamous shipwrecks.

A modest park memorial pays tribute to one of the Titanic's most revered storylines.

A museum marks and documents the site of the Titanic's launch.

A dilapidated dock tells the story of Titanic’s missed arrival.

A remarkable geological formation resembling a forest made of stone.

An abandoned village that doubled as "The Hunger Games"' post-apocalyptic wasteland is up for grabs.

70,000 empty bottles of Coke comprise an ad seen only from the air.

A wild west cemetery in Tombstone, Arizona, provides a window into the Old West.

Once a year, ambitious surfers can ride the world's largest river.

The lynching and burial site of America's first train robbers.

This annual Belgian water race attracts bathtub captains from all over the world.

A stunning, abandoned limestone quarry in southern Indiana provided the stone to erect the Empire State Building.

The sci-fi villain is a little-known inhabitant of the U.S. capital's largest cathedral.

A historic presidential getaway on the continental United States' southernmost island.

A man-made island in scenic San Francisco Bay.

A tiny islet just off Long Island offers a wealth of infectious curiosities.

One tree's homage to soles past and present.

A 30-year-old Sycamore tree grown from a seed taken to the moon and back.

This mysterious hill seems to pull objects uphill.