Spanish architects used seized Muslim gravestones to rebuild parts of the fortress.

Spain's largest bullring offers a unique glimpse at architecture and history.

The final resting place of the great navigator, or maybe his brother.

The world's largest wooden structure.

Spain's unique Mosque-Cathedral has been a place of worship for both Muslims and Christians throughout its history.

A lush indoor jungle fills this bustling Madrid transportation hub.

Eat the ultimate iteration of Portugal's most beloved pastry.

Elaborately carved to showcase the glorious wealth that the age of exploration brought to the Portuguese empire.

This small chapel is built of human bones and decorated with a golden skeleton.

A 16th century chapel decorated with bones, skulls, and entire bodies hanging from the wall.

This tiny square mile of Canadian sand was once considered the world's smallest desert.

This picturesque beacon was built to keep boats safe shortly after the Civil War.

An angular maze of concrete in Grand Rapids acts both as public art and as a staircase for fish traveling upstream.

An unlikely beach paradise of giant sand dunes lies between two lakes just a few minutes from Michigan's cherry country.

This 19th-century building inadvertently preserved the handprints of its builders within its walls.

The secret city built by the Manhattan Project.

This replica of the Greek structure is in the heart of Nashville.

The author's beautiful and historic home is also a fully functioning goat farm.

This shifting North Carolina sand dune is an odd little desert surrounded by oceanic forest life.

The tech giant built three enormous glass orbs in Seattle so employees could work inside a rainforest greenhouse.

Originally a brothel during the Klondike Gold Rush, this bar once used dolls to denote when ladies were working.

A classic gold rush hotel can be expected to pick up some ghosts along the way, and the Golden North is no exception.

A monument commemorating the role of Alaska's native Tlingit guides in the Klondike Gold Rush.

The facade of this relic from the Klondike gold rush is decorated with over 8,800 pieces of driftwood.