This unauthorized stone mermaid was secretly carved out of public stone before being permanently preserved.

Nonprofit art center that promotes outsider, intuitive, and self-taught art.

A century-old network of freight tunnels underneath the city's historic business district.

Shop of curiosities with a dinosaur museum tucked in its basement.

A hollow cement depiction of time's inexorable effect on the human body.

A gothic church spire sits atop this skyscraper, the tallest church in the world.

A haunting statue called "Eternal Silence" has quite the reputation among visitors with active imaginations.

An antiquated German apothecary on Chicago's North Side.

An enormous park-like oasis, full of famous Chicagoans' graves.

A science teacher's dream.

A lush green oasis in the middle of Chicago.

A giant bronze coil of feces is both a tribute to doggie defecation and a reminder to pick it up.

A monument to the art of slicing people open.

This morbid, delightful curiosity shop offers everything from animal bones to human teeth.

This shop for all your super spy needs hides an educational secret.

This massive stained-glass masterpiece is thought to be the largest Tiffany dome in existence.

This whimsical Oz-themed park had a wonderful impact on the surrounding neighborhood.

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

Each summer, the migratory bats living beneath the bypass form "batnadoes" at dusk.

A mountain range on an active U.S. Navy base hides thousands of mysterious prehistoric rock carvings.

The blinking light atop the iconic landmark has been sending secret messages for decades.

The decor of this Hollywood movie palace just barely predated the opening of King Tut's tomb.

These two monoliths have stood at the entrance to the neighborhood since the days it was called "Hollywoodland."

A statue commemorating the heroic life of a Viking postman who was the Godfather of California skiing.