The doodles of a genius line the walls of a secret room under the Medici Chapel, where they were hidden for nearly 500 years.

Stalactites and stalagmites in a beautifully lit cave.

Renaissance villa and gardens complete with a tormented colossus.

Thousands of well-dressed mummies below a monastery.

A collection of anatomical samples from one of the first anthropologists to suggest that humans reached North America by crossing the Bering Strait.

Two stunning 17th-century libraries and a cabinet of curiosities.

This Scottish bridge seems to compel dogs to leap to their death.

A Victorian Gothic masterpiece housing a world-class collection of rare books and manuscripts.

This hidden green space is the city's second largest conservatory.

Shakespeare, David Bowie, Dr. Who, the Saxons, Druids and Romans are all claimed to have all made their mark on these massive man made tunnels.

Giant, friendly pelicans in Central London, the most unlikely of places.

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.

A small island less than half a mile from Venice is a forbidden island with a dark and twisted past.

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

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

A 16th-century horror show built in a lovely Italian garden.

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

Mysteriously stacked storefront paths give this medieval British town an iconic style like none other.

Spend the night in this formerly abandoned traditional Scottish village.

A 2000-year-old Roman amphitheater lies just below Guildhall Yard.

An Oxford museum where visitors can have tea with the Mad Hatter and climb through the wardrobe to a fantasy land.

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

The gloomy ruins that inspired Bram Stoker to bring Dracula to life.