Guns that have been defending San Francisco since 1904.

This residential door allows San Francisco muggles a glimpse at the wizarding world.

A famous alternative culture epicenter and where Joplin serenaded young hippies.

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

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

An overlooked and unassuming engineering marvel.

A still functioning vaudeville carousel that has operated for over a century boasts a colorful menagerie and past.

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

The one-time watch house for incoming ships at the Golden Gate now stands abandoned and hidden in trees.

A winding path built in secret on the edge of the continent.

Soldiers were buried next to Lee's house in the center of Arlington Cemetery to dissuade the general from reclaiming his property after the war.

Giant works of art interspersed throughout meadows and woodlands offer a new discovery at every turn.

These unusual rooms on wheels are holdovers from the 1960s.

This lovely picnic spot featuring thunderous jet landings is an aircraft spotter’s dream.

A semi-scholarly approach to sex.

An interesting decoration on this historic site, this weathervane comes with as many legends as it does questions.

This replica of the Greek structure is in the heart of Nashville.

Macabre headstones carved with winged skulls, dancing skeletons, and pithy reminders of impending death.

Whisper secrets in a busy station only to be heard on the other side of this acoustic arch.

A former waterfront market is now in the center of town due to some interesting Boston engineering.

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

A super-sized promotional trick that is now a D.C. landmark.

The only intersection in America where the buildings on all four corners were built pre-Revolutionary War.

This mausoleum is the final resting place of one of St. Louis's richest and most tragic families.