The Denver airport is guarded by a 32-foot-tall sculpture of a demonic horse.

Quirky water tower advertises the long-gone Brooks Tomato Products Co.

Fresh wooden posts have been added to ancient holes to recreate a primitive henge clock.

Once one of the world's great cities, Cahokia was a place of religious worship, trade and mass human sacrifice before being mysteriously abandoned.

A historic house in St. Louis was plagued by a series of suicides committed by family members involved in a successful brewery.

Less a museum than a bizarre fantasy world created by artists and engineers.

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.

A 98-room castle in the middle of Toronto that bankrupted a 19th century electricity multimillionaire.

The narrowest street in Canada was once a spot for dastardly doings, now a historic piece of Chinatown.

This shallow cave got its name from copious amount of human bones found inside.

The fifth-longest suspension bridge the world, connecting one Michigan peninsula to another.

Strange physical sensations and optical contradictions keep visitors coming back for more.

Astounding collection of coin-operated games and automata.

Island where motor vehicles are banned -- home to the only carless highway in the United States.

These grassy undulations on a stretch of University of Michigan campus aren't bad landscaping, they're art.

A park and memorial dedicated to the victims of the deadliest school massacre in American history.