It's safe—and permitted—to walk across these twin natural sandstone arches.

The fifth-longest natural arch in the world, and the longest outside China.

The Jewish section of the famous Boothill Graveyard was abandoned for nearly 100 years.

A wild west cemetery in Tombstone, Arizona, provides a window into the Old West.

An old saloon in the West filled with history, and according to some, a few dozen ghosts.

This isn't your average roadway—it's actually a National Park and a transportation pioneer.

The romance of early commercial flight still fills this Art Deco destination.

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

A former major munitions plant that has been converted into a sprawling art space.

This colonial tavern played host to George Washington, Thomas Jefferson, and other famous early Americans.

The narrowest house in America is seven feet of pure spite.

An original apothecary from 1792.

This sculpture by artist Fritz Keonig survived the 9/11 attacks and now stands as a monument to the victims.

One of the Seven Wonders of the Modern World holds the world's tallest metal staircase.

The second-largest cave chamber in the world was discovered in 1898 by a 16-year-old and a friend known as "Pothead."

An organ located deep within a cave, whose "pipes" are the geological features of the cave itself.

Headquarters of the legendary clairvoyant's readings, spiritual hospital, and massage school.

This statue is dedicated to Grace Sherwood, the last person in Virginia to be convicted of being a witch.

A genuine Tudor manor transported piece by piece from England.

The final resting place of two (or three) presidents, one vampire, and 18,000 Confederate soldiers.

This 29-ton granite ball spins around at the slightest touch thanks to a scientific phenomenon.

This museum devoted to the gothic author holds such interesting ephemera as his socks and walking stick.

The heroic sled dog of the 1925 serum run is preserved in taxidermy.

One of the most elaborate displays of Jellyfish is on display at the aquarium.