A brilliant turquoise lake in the mountains.

Built entirely of interlocking pieces, construction of this Chinese Muslim house of worship required zero nails.

This quaint Hungarian railway system is operated exclusively by children between the ages of 10 and 14.

The abandoned "Red Star Train Graveyard" is the final rusting place for precious artifacts of train history.

Once the home of a hermetic monk, this cave now houses a small church.

This Hungarian castle was built out of cardboard and wood until it proved so popular that it got upgraded to stone.

A trail of iron footwear stands as a monument to the thousands executed along this riverbank during WWII.

For nearly a year, General Ulysses S. Grant was based here during the American Civil War.

A bronze sculpture of Lenin’s likeness outside Havana surrounded by 12 human figures in solidarity with the Bolshevik Revolution.

This shifting North Carolina sand dune is an odd little desert surrounded by oceanic forest life.

Rippling sand dunes frozen in the Arizona rock.

An exquisite tunnel of cascading flowers.

This astonishingly geometric cave has inspired everyone from Jules Verne to Pink Floyd.

London's creepiest cemetery was once the site of dueling magicians and mobs of stake-carrying vampire hunters.

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

A former mental hospital founded in the 1930s by a eugenicist who advocated for the forced sterilization of patients.

A railroad tunnel that, upon its completion, was considered one of the engineering marvels of the modern world.

The ruins of this Thomas-Jefferson-designed mansion have been left to crumble since the Christmas Day they burnt down.

Take an otherworldly journey in a school dedicated to out-of-body experiences.

The flower-shaped temple in Virginia aims to transcend the boundaries of the world’s religions.

A medieval castle in the middle of rural Texas.

Twelve hundred stone carvings guard this off-the-beaten-path Buddhist temple.

Along the historic Mother Road is an old gas station with a secret counterfeiting past.

After suggesting criminals be burned to death on this rock, a king's advisor suffered his own punishment.