An underground city of salt.

This unassuming museum's slogan translates to “there is a limit of sadness, anxiety has no limits."

On the Spree bank, discover one of the last reminders of a symbolic wall that divided, and was torn down by the people.

Construction of Barcelona's iconic (but controversial) church is expected to be completed in 2026—a century after the death of its architect.

This Industrial Age architectural and engineering gem helps visitors and residents alike traverse Lisbon, “The City of Seven Hills.”

Once a black market electronics marketplace, now an otaku shopper's paradise.

After a profound show of devotion for his master, a dog becomes the symbol of loyalty for an entire nation.

A small museum in the Bay of Pigs gives the Cuban perspective on the famously failed U.S. invasion.

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.

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

Deep in the Guatemalan jungle stands an ancient pyramid that once marked the reign of a king.

These roaring primates were considered a divine creature in the cosmology of the Maya.

Monkeys inhabit the lush forest surrounding ancient Mayan ruins once considered sacred.

The sister plane of the C-123 shot down during the Iran-Contra Affair has found a new purpose in retirement.

Some of the world's only freshwater seals live in one very special lake in Russia.

Gargantuan home of Russian science.

Hidden in a metro shop under a shopping mall, this small museum tells the story of one of the world's largest urban transit systems.

This massive monument honors the first human in space.

This building holds the embalmed remains of the leader of the Bolshevik Revolution.

The gorgeous entrances into the city's underbelly look more like grand halls than subway stops.

Two stunning 17th-century libraries and a cabinet of curiosities.

Despite attempts by local police to discourage it, Beatles-inspired graffiti has been a means for artists to air grievances for decades.

Nine bronze hands protruding from a wall honor the student uprising that led to the fall of Czechoslovakia's Communist government.