Gilded heaven for philatelists and architecture freaks, still in full working order despite sitting atop tremulous ground.

The only castle in North America to ever house European sovereigns.

Frida Kahlo's childhood home, now a museum of her life and works.

Whisper secrets in a busy station only to be heard on the other side of this acoustic arch.

The magic's in the hole!

The seamy, underground secrets of Portland's criminal past.

The twin towers in this Chicago fountain use 50 foot tall video screens to spit on people.

What's left of the ruins of the 1893 Columbian Exhibition, or World's Fair, also known as the White City.

This historic hotel invented the chocolate brownie.

This massive stained-glass masterpiece is thought to be the largest Tiffany dome in existence.

More than five miles of underground passageways.

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

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

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

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

A Florida college boasts the world's largest single-site collection of structures designed by Frank Lloyd Wright.

Step back into the glory days of Florida's nascent tourism industry at this Gilded Age palace.

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

St. Augustine's record-setting narrow street was designed to protect against pirates.

Manatees congregate around a power plant's discharge canal where the water is especially warm.

A monument celebrating the idea of reaching inaccessible places.

Meet manatees face-to-face at this zoo for native species.

A luxuriant botanical garden below sea level.

The only Florida state park with publicly accessible caves.