The final resting place to 300 Victorian-era pets hides inside the city park.

Catacombs turned marketplace.

This hidden rooftop garden in downtown London offers a quiet respite from a bustling city.

A clock designed to run with perfect accuracy for 10,000 years.

This shop and gallery is a modern-day cabinet of curiosities, unassumingly positioned along an urban thoroughfare.

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

This churchyard arbor is surrounded by hundreds of gravestones placed there by author Thomas Hardy.

An abandoned tank sits in an empty London lot as a symbolic middle finger to local city planners.

One of the few remaining casualties of the London Blitz, this destroyed church has become an enchanting public garden.

Ship-sized kinetic sculptural fantasy.

Hear the quietest sound from across the dome.

This London plaque marks the spot where David Bowie's famous alien made his debut.

This luxury shopping lane has been protected by its own tiny police force for over a century.

London's smallest police station is barely the size of a phone booth.

The "beautiful" equation predicting the movement of all electromagnetic particles is engraved in front of Newton's tomb.

One part local history, 99 parts gruesome haunted house.

This whimsical castle of grottoes was the labor of love of a French postman, and one of the greatest achievements of outsider architecture.

This astonishingly geometric cave has inspired everyone from Jules Verne to Pink Floyd.

A 'living museum' in Leiden, the oldest of its kind in the Netherlands.

This immaculate and historic water garden culminates in a massive stone dining table with an inset fountain for chilling the wine of the Cardinal's guests.

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

The burning of this 12th-century church kicked off a campaign of Norwegian Black Metal terror.

Walk behind a 50-meter-high waterfall.

Walk 2,300 feet above the ground on the "Troll's Tongue."