Guns that have been defending San Francisco since 1904.

Beneath the southern end of the Golden Gate Bridge is the “Gibraltar of the West Coast,” a fort built to protect the San Francisco Bay from naval attack.

At the base of the Golden Gate Bridge, a small sign basically begs for a high-five.

One of the world's oldest and most massive living organisms is a grove of quaking aspens.

Now abandoned, the first reinforced concrete bridge in Alabama still stands over the Pea River.

Six separate cemeteries became one, on the grounds of a former schoolhouse.

A small house sits between two huge rocks, with its back to the sea.

A little-visited ghost town state park offers a glimpse into Montana’s "Silver Queen."

Accessible only at low tide, the deserted island is dotted with World War II ruins.

A tribute shrine where the Space Invasion street art movement started.

Anonymously sculpted and donated, these sculptures made from poetry books and pages are sprinkled around the city.