The "World's Largest Underground Business Complex," a 55,000,000-square-foot city underneath Missouri.

Disney World's very first waterpark is now an abandoned ruin being reclaimed by the swamp.

These constructed wetlands naturally filter millions of gallons of treated wastewater every day.

The sign that drew attention to a young boy's cucumber stand is now the name of his fruit superstore.

Found: Garden of Eden in Miami-Dade County, Florida.

The highway's southernmost spot is a beloved local attraction.

A small poultry graveyard in the courtyard of a popular Key West watering hole.

A building so large that it has its own weather.

Former villa and estate of James Deering developed to preserve native tropical forests.

The world's largest occupied bat houses hold hundreds of thousands of flying mammals.

A monument celebrating the idea of reaching inaccessible places.

An abandoned water sports stadium that has become a haven for graffiti and decay.

The behemoth beasts engaged in an epic battle is the second-tallest statue in the contiguous United States.

This Florida sinkhole hides a rainforest-like micro-environment in its depths.

St Bernard de Clairvaux Episcopal Church, better known as one of the oldest European buildings in the Western Hemisphere.

A mysterious castle built as a monument to lost love.

This sculpture commemorates the first instance of an American president pardoning a turkey.

There's something big lurking beneath the surface of this tiny Oregon park.

On the Oregon coast is a natural hole that seems to be draining the sea.

This extravagant Art Nouveau rest stop features a million-dollar view of the Columbia River.

This unassuming cheese empire in rural Oregon churns out more than 150,000 pounds of cheese each day.

The first park built over a freeway is a brutalist masterwork.

A giant Troll lurks under one of Seattle's oldest bridges.

A wall of chewing gum moonlights as collective art.