A 2,000-year-old Adena burial mound located along a busy street in Columbus, Ohio.

A natural dome made of volcanic glass in Inyo National Forest.

The entrance to this sinisterly named tunnel hides behind a Tim Hortons.

A psychedelic labyrinth on the San Francisco bay.

A monument to a Native American leader who was known for never breaking a promise and met his end after signing a deal with white settlers.

The world's tallest doric column is this Ohio monument to a naval victory in the War of 1812.

This naturally heated mountainous creek has created a group of neon blue pools of potentially deadly boiling water.

A charming desert roadside bakery that produces 10 times more bread daily than it has residents in its town.

Take a drunken tour inside the world's largest known geode.

The huge granite obelisk that towers over a small California town.

Aqueducts have dramatically changed this old lake, now home to tufa towers and its very own species of tiny brine shrimp.

Towering basalt columns, a creation of fire and ice.

Crypt mausoleum in cathedral's basement contains relics of third century Roman martyr, Saint Vibiana.