Tiki luxury on Nob Hill.

Get lost in this haunting fairytale art walk through a man-made eucalyptus grove.

A tiny theater hidden in an alley plays a constant stream of short silent films for anyone willing to peer through the peephole.

A 140-year-old castle with underground caves hidden in San Francisco.

In all of the 29 years it was in operation, no prisoners ever escaped successfully... or so they claim.

An artsy hidden staircase leads to breathtaking views of San Francisco.

A huge musical instrument played by the ocean.

A psychedelic labyrinth on the San Francisco bay.

A collection of 20th-century automata, penny arcade games, and musical contraptions.

Once the last route taken by condemned prisoners.

Inside this Krakow church, an explosion of psychedelic color.

A commemorative plaque hides a door that leads down to the New York Public Library's underground book bunker.

More than a million titles fill the labyrinthine shelves of this prestigious private library.

Standing atop 2nd-century Roman ruins, this church is one of the oldest and most iconic in Old Cairo.

An ancient instrument used to measure the waters of the Nile so Egyptian farmers would know whether to expect famine or flood.

The largest known Ancient Egyptian obelisk.

This North African stone complex is considered to be the oldest astronomical observatory on Earth.

A shrine on the shores of the Tigris.

The sacred shrine of the Yazidis.

9th century Abbasid mosque, damaged in modern warfare.

Wander through more than 20,000 square feet filled with an amazing collection of orchids.

Art Deco urban decay at this historical building.

Bigfoot prints, Feejee mermaids, and haunted dolls on display in a tiny North Carolina town.

This woodland architectural installation acts as a camera obscura for the heavens.