A 2,000-year-old computer demonstrates remarkable engineering and astronomical precision.

America's only nuclear missile silo open to the public.

Friction between grains of sand cause a curious "singing" sound.

Palatial mansion estate used in films including "Flowers in the Attic" and "The Witches of Eastwick."

The inspiration for H.P. Lovecraft's horror stories and Batman's Arkham Asylum is now a condominium complex.

This amended headstone marks the grave of a participant in one of the most successful military deceptions of all time.

Single runway interrupted by a busy road that cuts across its middle.

A seemingly endless landscape of pure salt stretches far across Bolivia.

This huge pile of volcanic boulders hides a stunning network of secret grottoes.

Iceland's "Smoky Valley" is a beautiful river that is shrouded in a constant cover of steam clouds.

Rare karst landscape eroded from a flat seabed.

Old-fashioned knowledge and modern engineering create the world's only rotating boatlift.

A part of the world's largest marsh seems to be growing bright red Martian grass.

Unsurprisingly, Holland is home to one of the most magnificent flower gardens in the world.

Three bridges and one giant canyon make up this fantastic Spanish settlement.

This abandoned mansion has a window for every day of the year, and is a temple for ghost hunters.

Madrid's romantically ornate crystal palace has been offering shelter to plants and art for over a century.

Arcadia is home to a haven for nature geeks and 80s TV lovers alike.

Dolphins, ancient clams and hundreds of waterfalls make this one of the world's top tourist destinations.

Colorful and chaotic stacked hotel in North Holland.

Venice's "Island of the Mad."

A beautiful, dense forest in the shadow of Mount Fuji, with a tragic reputation.

This modern French ossuary contains the jumbled bones of 130,000 WWI soldiers.

The only structure left with direct ties to the Salem witchcraft trials of 1692.