Started as a kitchen garden, now the second largest botanical garden in the world.

Hot springs monkey spa in the middle of Hell's Valley.

Medicinal spa created with the discharge from a geothermal energy plant.

The feral felines of Roosevelt Island have a small army of allies and an abandoned hospital all to themselves.

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

An easily overlooked stretch of ornate window fronts and gaslight lamps that could be right from the pages of Dickens.

This massive stained-glass masterpiece is thought to be the largest Tiffany dome in existence.

A charming 17th-century alley is lined with secondhand bookstores and antiquarian shops.

Enormous lake at the bottom of a unique cave system.

Shop selling 500 flavors of soda has something for everyone.

This iconic Parisian bookstore doubles as the "Tumbleweed Hotel" for traveling writers.

An Amsterdam street lined with antique shops each one dedicated to a different obscure collection.

Hidden in the hills of Hollywood, this secluded Oz-themed garden is dotted with dozens of thrones.

A semi-scholarly approach to sex.

Resting place of Hollywood's immortals is also site of summer film screenings.

This Boston medical museum features the skull of the famous medical case of Phineas Gage.

Tucked in the back of this amazing antique store is an important piece of medical history.

Under the right circumstances, this waterfall in Yosemite briefly turns a luminescent fiery orange.

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

The only swimming pool listed on the National Register of Historic Places is emptied and refilled each day with naturally filtered water.

This whimsical Oz-themed park had a wonderful impact on the surrounding neighborhood.

It should come as no surprise that the best view of the Hollywood sign is from Batman's lair.

Kings Cross Station pays tribute to its role in Britain's best-selling book series.

This massive library holds what was once the largest book collection in the world.