Henry VIII's forgotten castle was built by the gunpowder-obsessed king to be defended solely by cannons.

This centuries-old hotel hides a network of secret cellars and passages once used by smugglers.

The Tudor-style cottage in the middle of the square is not quite what it seems.

A terrific purveyor of natural history objects and curios.

The only surviving piece of Copenhagen's 16th-century defensive wall.

This bridge's unique architecture honors nautical heritage and encourages self-awareness.

The world's first combination ski slope and power plant.

Climb to the top of its spiral spire for spectacular views of Copenhagen.

Danish tourist destination well known for open stalls where vendors sell marijuana on the street.

Swedish skyscraper with a 90° twist.

This chimerical bridge/tunnel appears to dead end right into the sea.

This millstone commemorates a gruesome tale that may have been the source of the city's name.

One of the few remaining examples of 19th-century London’s attempt to clean up its reputation.

This one has sailed five times as far as Sir Francis Drake's famous ship.

Ship-sized kinetic sculptural fantasy.

Wedged between two buildings at the Great Ormond Street Hospital is this secret music installation.

The monster at the center of the Darwin Center Spirit Collection.

This iconic high-rise residential block was one of the last to be built in the Brutalist style.

This beautiful deer park was built so King Charles I and his court could go hunting while escaping a deadly plague outbreak.

This display showcases the culinary equivalent of steel-toe boots during World War I.

The wooden grave marker of a railroad worker who died in a freak whirlwind.

Soak up some local history in this restored Edwardian era swimming pool.

This natural history collection contains the bones of a circus elephant that seem to be chasing a whale skeleton.

This magical museum celebrates the life and work of a seminal children's book writer (and occasional spy).