A geological mystery on Camelback Mountain.

The installation’s official name, “You Who Are Getting Obliterated in the Dancing Swarm of Fireflies,” says it all.

The splendor of this 17th century golden chapel has led it to be called the "eighth wonder of the world."

An Aztec temple, the largest man-made pyramid in the world, sits buried in earth with a Spanish church set on top.

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

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

This Transylvanian church has changed its denomination four times.

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

The European towns of Brașov and Râșnov each have proud signs reminiscent of the Hollywood sign.

A stunning 18th century pharmacy and medieval chemist's collection.

Gigantic Romanian salt mines used to heal respiratory conditions.

Something's watching you.

Romania's only crater lake with water as pure as if distilled.

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

This fairy-tale castle would make Dracula (who is said to have been imprisoned there) jealous.

This elaborately decorated, fairytale-like Romanian royal palace is one of the most striking castles in Europe.

This massive underground salt mine now holds a sci-fi theme park in its depths.

Baroque celebration of the end of the Great Plague of Vienna.

The topiary maze at the Habsburg hunting lodge.

This towering totem holds the title for the tallest in the world but only according to some.

What happens when a sculptor has to find a way around a 100-year-old copyright.

Come for the flowers, stay for the bats!

From Austrians to Nazis to Soviets, this historic Budapest fortress has a history as complex as the city itself.

Built in 1870 at the bridge that connected Buda and Pest, this spectacular incline railway was almost lost forever during World War II.