Once one of the most polluted caves in America, now an environmental success story and a museum dedicated to caves.

The world's longest known cave system.

A model of a dinosaur that was named for Andrew Carnegie stands outside the museum that also bears his name.

A building so large that it has its own weather.

The walls of America's oldest masonry fort famously "swallowed" cannonballs.

A tribute to Ponce de Leon's supposed quest for eternal youth.

The land is home to swimming ponies and a legendary 18th-century treasure.

The taxidermy remains of the most popular pony in children's literature.

Chase waterfalls, hiking trails and more.

Frank Lloyd Wright’s most iconic home dangles over a Pennsylvania waterfall.

An abandoned stretch of highway, deteriorating next to the operational one.

This shop filled with oddities and knick-knacks is named for a 19th-century charlatan.

A beautiful oddities shop crammed with strange and morbid curiosities.

Long hidden under grime, the politically radical murals of a little known Yugoslavian master are finally getting their due.

Discover these whole-house works of art in Pittsburgh’s Troy Hill neighborhood.

Playful installation outside a Pittsburgh art gallery might feature the world's longest historic-plaque text.

Witness these plains giants that nearly became extinct in the late 1800s.

It marks the spooky spot where the bodies of two young boys were found in the 19th century.

This stone polylith serves as both a 100+ year old experiment and monument to the history of science.

Considered by many to be a local landmark and treasure.

The mortal remains of a Russian prince, priest and paranormal investigator who came to America in 1792.

This dramatic rail curve was once the target of a failed Nazi attack.

Behold the rickety glory of one of the oldest roller coasters still standing.

Once home to a wealthy ironmaster, this 19th-century mansion now holds unique relics from Blair County's past, and perhaps the spirits of its former occupants.