Bring your own cardboard to the slippery slopes of concrete hidden in a neighborhood park.

A focal point of in Denver’s skyline for over a century, inspired by a Venetian basilica.

This Nevada lake holds its titular natural pyramid and, if the legends are true, a number of dangerous spirits.

One woman's Viking Castle on Lake Tahoe.

This historic estate on the east shore of Lake Tahoe was home to an eccentric millionaire (and his pet elephant, Mingo).

Eastern zen meets Western grit in these four little trees growing out of a rock on Lake Tahoe’s Nevada shore.

The smallest country in the world.

Gold Rush ship-turned-hotel buried underneath San Francisco's financial district.

This tall and trim architectural oddity is one of the skinniest buildings in San Francisco.

San Francisco's oldest surviving monument and meeting place for 1906 survivors.

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

The stones that traveled from Spain to eventually become a holy place for San Francisco's nature worshippers.

Created in 1972, the famous sculptor's intricately detailed monument to San Francisco is overflowing with city landmarks.

The original place where water met land in the City by the Bay is outlined in brass.

The remains of a 12th-century chapter house in Golden Gate Park.

An overlooked and unassuming engineering marvel.

This turn of the century masterpiece has a mysterious goaty interloper.

Adolph Sutro's little-known, geographically inaccurate, deprecated monument.

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

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