This historical Netherlands fortress still bears the marks of its single siege.

This beautifully designed star-shaped fort was the premier defense system of the late 1500s.

The site where one of the most famous poems of World War I was composed is preserved to honor the legacy of the work.

Hiding the longest subterranean river known in the world.

A fantastic castle rumored to be the birthplace of King Arthur.

Surreal riveted sea forts once protected the Kent shores from German attack.

The largest of London's subterranean rivers and once a mad, bad center of London life.

Winding paths and ramshackle mausoleums in the oldest "park cemetery" in London.

Famously misunderstood wonder of the ancient world

The sign at the garden gate reads: "These Plants Can Kill."

The John Snow Memorial marks the epicenter of London's 1854 cholera epidemic.

A plaque marks the underground site of one of London's "lost rivers."

Six ravens are kept captive (but well-fed) at the Tower of London to prevent the fall of the Crown.

A recently restored Shoreditch landmark with ties to Jack the Ripper.

Murals of the wild parties once held on the frozen River Thames.

Richard III supposedly disposed of his nephews' bodies here in an effort to seal his claim to the throne.

Children's hospital in London that operates on royalties received from Peter Pan, which J.M. Barrie signed over in 1929.

This pump on the bad side of Victorian London betrayed a horrifying revelation about the water supply.

The breadfruit-adorned final resting place of the infamous Captain of the HMS Bounty.

Shiny Brutalist box commemorates a pioneer of electricity and houses a railway transformer.

The townhouse where the English poet created some of his most influential work has been preserved in tribute.

A museum wholly devoted to juvenescence.

The remains of an ancient Roman teenager are memorialized at the base of a modern London landmark.

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