No telescopes, no power, no gift shop: The Observatory of Chichen Itza, one of the world's oldest observatories, takes astronomy back to basics.

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

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.

This Transylvanian church has changed its denomination four times.

A fire once nearly devoured this gorgeous 14th-century Gothic cathedral.

The possible imprisonment of Vlad the Impaler here earned the medieval castle its nickname, "Dracula's Castle."

This crumbling medieval basilica once attracted pilgrims by the thousands to collect a miraculous dust that formed above the saint's tomb.

Legend says if you stick your thumb in the hole and it gets wet, your wish will be granted.

Carvings in Turkey's Marble Road may have directed ancient Romans to a hidden brothel.

A small etching on the white marble parapet was written in runic script by a Viking mercenary.

Roman ruins top white travertine terraces formed by ancient hot springs.

These "50 Fortresses" have been unearthed in the ancient oasis of Khwarezm.

Ancient barriers wrap around what was once an important stop along the Silk Road.

The field of tiny caves that mark this Chinese cliffside are each their own historic Buddhist temple.

A harrowing trail up a mile-high mountain.

The embalmed remains of the communist leader lie within a custom crystal coffin.

This probably wasn't what Mao had in mind.

The most famous location in China was home to whole dynasties worth of imperial rulers.

In Kazakhstan, a colorful cathedral with many lives once survived the most powerful earthquake in the region.

Dedicated to a Bolshevik revolutionary, this museum is a true time capsule of the Soviet era.

This retro, UFO-like structure is a remnant of the Soviet-era circus.

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

An outstanding piece of retro Sci-Fi architecture built into a sacred mountain.