The enormous smoke hides within a little known, semi-secret exhibit inside Havana's Morro Castle Historic Park.

Once a favorite playground for the world's most illustrious guests, Hotel Nacional's secret weapons and bunkers reveal a more menacing side to its golden history.

After the Cuban Revolution, the famous rum company had to leave their swanky headquarters behind.

Earth's greatest purely vertical drop at 4,101 feet.

This igloo-shaped landmark in Iqaluit serves as the seat of the Diocese of the Arctic.

A modern version of the stone cairns built by the Inuit.

This chilly Canadian hotel has a four-month lifespan due to the unusual material it's made of.

This lovely, if imposing, piece of Canadian gothic is possibly the most photographed hotel in the world.

The falls were named for the mistaken idea that they were the ones pictured on the Canadian $5 bill.

This 1967 experiment in modular architecture was designed to be a new model for urban living.

Its columns were all carved from the same white oak tree.

City law dictates that this mountaintop cathedral containing the heart of a saint is to remain the tallest building in town.

This North African stone complex is considered to be the oldest astronomical observatory on Earth.

A nun spent 16 years painting the stunning Celtic mural that covers the interior of this WWI memorial.

A Gothic cathedral created from volcanic rocks.

Poland's oldest salt mine has nearly everything one needs to live underground forever.

The inverted pyramid design of this station stands out amid Bratislava's urban landscape.

Also known as the Blue Church, the building was consecrated to the daughter of Andrew II.

This spaceship sculpture in the middle of the Slovakian capital looks like it just crash-landed.

A once-fairy tale mansion now stands in a state of disrepair.

The 3.8 billion-year-old rock proves that tectonic plates may have been shifting longer than we thought.

Greenland's first shopping mall also hosts the country's government.

Thousands of letters to Santa get delivered to this mailbox in Greenland.

These eight mummies are the best-preserved human remains ever discovered in North America.