Collapsing castle on the Hudson river was once the storage site of military surplus business.

A village on the east coast of England that has almost completely eroded into the North Sea.

Mausoleum and Holy Seat of Antiochus I of Commagene.

A perfectly circular stronghold constructed in the 10th century is now a nucleus of Viking culture housing a museum, village, and reenactment of an epic Viking battle.

The engineering wonder and pleasure dome of a much-maligned emperor still holds undiscovered secrets.

A giant gun barrel in Barbados that once hoped to shoot outer space with science.

A small island with no monkeys but plenty of military ruins.

This large, circular tomb is the final resting place of the first emperor of Rome.

The southernmost outpost of the Russian Empire in colonial America.

This medieval hilltop village was abandoned at the end of the 19th century, after existing for more than 500 years.

A "house to which to flee" for settlers in colonial Pennsylvania.

A 400-square foot model of historic Quebec is the playing field for a state of the art light and sound show.

A winery built on the site of a Gallo-Roman estate uses historical tools to recreate ancient vintages.

This spectacular track has run continuously since 1882.

The remains of a historic ranch house that witnessed the Civil War battle dubbed the “Gettysburg of the West.”

This interpretive path lets you get up close and personal with dinosaur bones.

Dine aboard the historic Ghan train while retracing early explorers' journey through the Outback.

Few of the many visitors to this resort town know of its hidden Maya ruins.

The remnants of the base where US Army troops learned how to fight in extreme conditions.

The site of the little-known Pennsylvania battle that sparked the Seven Years' War.

This ancient market is often referred to as the oldest shopping mall in the world.

Blowtorches, tuna, and a jolly, chain-smoking proprietor mark this beloved street-food stand.

These characters from a Robert Louis Stevenson novel stand in an unlikely place.

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