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.

L. Frank Baum wrote part of the "Wizard of Oz" series in this wooden Victorian beach resort.

An inconspicuous footbridge beloved by San Diego locals.

Designed to commemorate the founding of the first settlement in Delaware.

An award-winning children’s garden enchants visitors at the intersection of natural beauty and fairy tales.

This weeping, 10-foot-tall sculpture was a maquette for a 9/11 memorial.

Barely visible foundations remain where Stow Lake’s “observatory” once welcomed visitors.

The oldest lawn bowling club in the United States.

This Alamo Square mansion is rumored to have hosted satanic rituals and other occult practices.

These subterranean storage areas hold emergency water reserves.

A one-ton statue of Steve Rogers beautifies the entry to a Brooklyn Bed, Bath & Beyond.

The return of something once considered a basic part of life.

Four cars from the old system were once on display, but were removed in 2014.

These three lighthouses played a fundamental role in the maritime life of Eastham.

These lush botanical gardens employ the most purrfect pest control force.

Queen Anne style apartment house built in 1886.

Known as the "Forgotten City" it was home to industry, riots, artists, squatters, and to one of the largest single disaster fires in New York City.

Built as a home for the Union Porcelain magnate in 1867, now the Greenpoint Reformed Church and home to a ceramic mystery.

2 square block factory in Greenpoint erected in 1936.

Home to first responders to Greenpoint's devastating oil fires.

The key to turning shifting dunes into the green oasis of Golden Gate Park.

This one-block alleyway is stuffed with street art that is colorful, cultural, and intensely political.

This 19th-century church is now a popular roller rink.

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