An opal mining town in the middle of Australia where people live, worship, and shop underground.

The longest fence in the world stretches over 3,000 miles to keep the dingoes out.

Florida castle built with aluminum printing plates.

An office built to look like a giant basket.

This shale formation along the Appalachian Trail once inspired the third president of the United States.

The last holdout of a pre-Civil War rebel who took the matter of slavery into his own hands.

This advertisement for talcum powder was painted on the rock face and has since defied removal.

The Grand Ole Opry's big voice came from a small home in rural Virginia where she was eventually buried.

An eponymous directional signpost erected by the first president of the United States.

Outsider art meets paleontology at this roadside reptile repository.

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

A glimpse at Walt Disney's vision for a "community of tomorrow," in miniature.

Electrical pylon in the shape of Disney's beloved mouse.

Possibly the most beautiful carillon in the world, set atop Iron Mountain in Florida.

A haunted hill that supposedly defied gravity.

A towering, steel behemoth that has graced the skyline of Lakeland, Florida since the early 1980s.

Nearly 200 prehistoric giants lurk among the trees at this theme park.

An octet of classic chrome trailers speared into the ground act as a tribute to the silver bullets of the open road.

This small museum gives visitors a chance to soak up the history of the "sponge capital of the world."

Florida’s first home built with eco-friendly hempcrete.

This abandoned NASA launch site is now a memorial to a trio of astronauts who were killed there.

A building so large that it has its own weather.

One-time winter retreats of prolific inventor Thomas Edison and his friend Henry Ford.

Like Mardi Gras, only everyone's a pirate.