A 70-foot replica of the famed Eiffel Tower.

Located inside a former bread factory, this museum explores a century of transportation history through innovations that were extraordinary or failures—sometimes both.

A natural sandstone bridge hidden in the Sewanee forest.

An ancient cave system in Tennessee’s Appalachian foothills converted to a 1,200-person music venue.

Hiding behind a grocery store is a spectacular cavern carved as part of an old limestone quarry.

This former maximum-security prison is creepy, sobering, and supposedly haunted.

This large cave is a summer home to thousands of bats and has a rich history dating back to prehistoric times.

All you ever needed or wanted to know about America's favorite whiskey, but not a drop to drink.

A recreation of the doomed ocean liner in the middle of the Smoky Mountains.

The hotel where Martin Luther King Jr. was shot is now a museum dedicated to his work.

Visit this playground of waterfalls, caves and sinkholes.

The mysterious wonder of an underground waterfall is illuminated by multicolored lights.

Wild lights and sound effects turn a walk through some caves into an eye-popping 1960s tourist attraction.

Enormous lake at the bottom of a unique cave system.

Nine of the very few concrete ships ever made in the U.S. are beautifully decaying off a Virginia pier.

A secretive collection featuring objects that were designed specifically for U.S. intelligence operations.

Giant busts of 42 U.S. presidents are sitting in a field in Virginia.

A particularly creepy abandoned hospital that sparks interest for lovers of the supernatural.

Once connected to the outside world by a single train track, this ghost town is looked after by the National Park Service.

America's post-nuclear-attack chambers of Congress.

One of the steepest streets in the United States makes an intriguing challenge for cyclists.

Found art has transformed this Pittsburgh neighborhood into a psychedelic dream.

Home to items never before seen by the public.

Cleveland's giant "free" stamp is a nod to the Civil War, but was misinterpreted for years.