The final resting place of the poets Shelley and Keats.

The glowing blue Nymphaeum of Emperor Tiberius.

2300-year-old Roman road connecting the empire.

The underground sanctuary of a mysterious ancient cult.

Pompeii's less famous neighbor is still revealing her secrets.

At the crypt of St. Mary of Eulogies and the Dead you are left alone to ponder mortality among piles of skulls.

This hidden Art Nouveau courtyard is an opulent feast for the eyes.

Hundreds of lucky felines haunt the ruins where Caesar was murdered.

The crypts of Capuchin friars decorated with the bones of over 4,000 friars, including an entire "crypt of pelvises."

An Italian crevasse filled with abandoned buildings gives visitors a look at the world without humans.

The bones of two medieval royal lions were discovered at the historic fortress.

These docile dragons are ideal inhabitants for the conservatory greenhouses.

A relic of Victorian grandeur hides beneath a busy South London road.

A statue of the legendary Celtic warrior queen who fought the Roman invaders stands in one of the cities she once destroyed.

Pop culture has helped to keep this iconic British building from being destroyed.

A network of concealed passageways lies within a busy London Underground station.

This 1920s Dutch barge is now a floating bookstore.

A hidden treasure in London with a rich medieval history, and the resting place of many luminaries.

A rare, flower-shaped example of Brutalist architecture in Switzerland.

The Swiss artist's bulbous and overgrown shape-shifting sculpture controversially graces the center of Bern.

A curious collection dedicated to human and animal anatomy and pathology.

Building Men of War and Indiamen from Holland's Golden Age.

A grassy pyramid named after a French battle.

This disused VLF radio station is no longer in service but the surrounding town still bears its name.