Every equinox this Maya pyramid puts on a spooky ancient light show.

Clap your hands at the base of the pyramid, and the song of a sacred Mayan bird will echo through the air.

A magical sinkhole on the Yucatán Peninsula is adorned with mini waterfalls and hanging vines.

These azure waters were thought to lead to the Mayan Underworld.

If you can look past the nearby sewer pipes, this urban sinkhole grotto is a mini-paradise.

An ancient system of freshwater caves filled with animal bones, including that of species long-extinct.

Beach instrument turned bed and breakfast.

Underwater art project will double as a massive artificial coral reef to help regenerate the damaged ecosystem.

The secret room where early Bolsheviks cranked out propaganda fliers on a smuggled printing press.

A small but hugely whimsical theater where marionettes play out the "The Battle of Stalingrad."

This architecturally eclectic fortress witnessed centuries of bloody turmoil, including the massacre of its ruling clan.

Legend says these stone structures are where the doomed citizens of a vanished village sent themselves to die.

A cylinder monument with a spectacular vista commemorates a friendship that some say never existed.

Rock-hewn monastery complex with hundreds of cave structures tucked away into the mountainside.

Underground monastery and fortress.

Ancient rock-hewn town that witnessed key events of Georgian history.

This hauntingly beautiful cemetery outside a medieval citadel is full of winding paths and ivy-covered graves.

Nine centuries-old fortresses guard the walls of this medieval Romanian city.

Packed to the ceiling with antique taxidermy and hunting arms.

A celebration of all things tacky, garish, and bizarrely creative in the Romanian capital.

Known as the Hintz House, this medieval pharmacy has been an apothecary's haven for nearly 450 years.

The romantic botanic tunnel feels like a well-kept secret.

Even drowned in an ocean of toxic waste, the remnants of this Romanian village stand tall.

The bust of Romania’s most notorious ruler, Vlad Dracula aka "Vlad the Impaler," keeps watch over the ruins of his medieval court.