A marvel of Byzantine engineering under the streets of Istanbul.

A temple devoted to inner esoteric mysteries located in a California commercial strip.

A historic arboretum and non-conformist, non-denominational park cemetery.

One of the world's largest collections of pathological specimens.

This wildly-tiled artist's palace is a living and growing account of the creator's life, loves, and labors.

A mysterious artist-run cabinet of curiosities and library.

A tongue-in-cheek arcade where the games are based on everyday life.

The only university zoological museum in London houses extinct animals, bizarre natural history specimens, and a Micrarium of microscopic creatures.

An unusual round church in London with a Templar past.

A kaleidoscopic warehouse-maze of handmade neon signs.

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

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

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

London's creepiest cemetery was once the site of dueling magicians and mobs of stake-carrying vampire hunters.

A Pythagorean funhouse that tries, successfully, to prove that math is the coolest thing ever.

Play heads or tails with thousands of different coins.

The mummified relics of an American missionary.

This collection of grinning ephemera has grown from basement to Brooklyn.

A quiet and contemplative oasis in the middle of New York's bustle and riot.

This hidden library of physiological ephemera contains centuries worth of knowledge on the vim and viscera of the human body.

Reverend Jen's unique museum/living room showcases her troll collection.

Hidden in Central Park's Ramble is a troublesome cave buried just beneath the surface.

A New York garbage depot holds a secret collection of weird and wonderful refuse.

A crumbling hospital from the 1850s on Roosevelt Island.