A Victorian-style home known as the “Castle on the Hill.”

Locals dubbed it the "Owl Building" because of its bird-like appearance.

This simple frog painting created by musician Daniel Johnston embodies the spirit of Austin.

A grove of colossal man-made flowers built to collect the sun's rays.

Home to the largest urban bat colony in North America, estimated at 1.5 million bats.

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

This private residence was the template for one of the most beloved television homes of all time.

San Francisco's urban bison herd has persisted in the face of extinction, development, and disease.

San Franciscans leave gifts and messages for the magical beings that live behind the tiny, mysterious door installed on a tree in Golden Gate Park.

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

Staircase winds down the side of Telegraph Hill through gardens, wild parrots flying overhead.

Olfactory delights in San Francisco's Botanical Gardens.

Its buzzing collection honors vibrator history.

Carnivorous plants, medieval aphrodisiacs, and the largest original wood structure glass conservatory in the western hemisphere.

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 sprawling cave network created by a lone lava tube.

Formerly secret, precariously perched boulders.

The ghostly remains of what was once the world's richest copper mine.

This whimsical stacked cabin looks like something out of a children's book.

Breathtakingly blue walls shimmer inside the "Glacier Behind the Town."

At the base of Steens Mountain resides an otherworldly desert.

Hundreds of handmade critters fill this tiny window gallery in the heart of Portland's Alberta Arts District.

This great stone guardian of the forest is a relic from the land's volatile volcanic past.