Bizarre Cavern.

From the sky, a kaleidoscope of color brightens the grey landscape of the San Francisco Bay.

After a short-lived attempt to bring America in line with the rest of the world, this road was left in metric.

Explore the largest pure gypsum deposit in the world, and go dune sledding while you're at it.

This rugged area of red rocks and arches is often considered one of the most beautiful places on Earth.

Hundreds of lucky felines haunt the ruins where Caesar was murdered.

The biggest drug trafficking passage between Mexico and the U.S.

The highest point in the state of New Hampshire, and while unlikely "the worst weather in the world," it sure seems that way to hikers.

Inspiring Herman Melville and Henry David Thoreau, Mount Greylock in western Massachusetts is the highest point in the state at 3,491 feet above sea level.

Largest Roman Catholic church in North America.

Home to items never before seen by the public.

The sci-fi villain is a little-known inhabitant of the U.S. capital's largest cathedral.

At 207 feet, one of the world's longest continuous escalators.

The site of the climactic scene from the classic horror film is now a historic landmark.

The remains of Martha, the last known passenger pigeon, serve as a tool to educate about conservation.

This grand gothic brewery has been pumping out suds for over a hundred years.

The summit Roosevelt conquered before he descended to become The Chief.

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

The site of Paul Revere's historic two lantern warning.

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

This massive tea kettle was once a promotional stunt for the Oriental Teashop.

An enormous, inside-out glass globe built in 1935.

Two thousand artifacts from around the world collected by one woman who loved to travel.

This bridge was the birthplace of a unit of measurement based on a fraternity joke.