Twenty-year effort to raise a castle using tools and techniques from the 13th century is now abandoned in the Arkansas woods.

A mysterious collection of stones stand outside a small New England town.

Palatial mansion estate used in films including "Flowers in the Attic" and "The Witches of Eastwick."

The Roman Emperor's lost summer home and grotto full of enormous sculptures sit along the Italian seashore.

The Cold War-era "underground Pentagon" is a sprawling subterranean hideaway for the Defense Department.

This splendid Versailles-inspired mansion has the largest French-style formal gardens in North America.

A virtually untouched "home on the hill" for the flora and fauna of Rhode Island.

This natural wonder drops 16 stories straight down through rare flora and streaming waterfalls.

Philadelphia boasts one of the best — and most often overlooked — traditional Japanese gardens in North America.

This palatial botanical garden is home to one of the largest pipe organs ever installed in a private residence, and a piece of Wood's cycad.

The sign at the garden gate reads: "These Plants Can Kill."

Lavish royal estate punctuated with heated greenhouses.

A tropical paradise just a short trip from the opera house is filled with beautiful winged creatures.

One of the oldest scientific gardens in Britain, containing more than 13,302 plant species in its core collection.

Three prestigious academic collections come together to create a world-class natural history museum.

This abandoned psychiatric hospital once housed more than 4,000 patients in the middle of a quaint New England town.

Constant erosion has created a surreal landscape of bleached and preserved fallen trees.

This lovely, if imposing, piece of Canadian gothic is possibly the most photographed hotel in the world.

Collection of antique taxidermy and natural specimens, near one of Paris's oldest flea markets.

A Parisian exterminator's shop whose storefront displays stuffed rats hanging from traps.

This innocuous-seeming building is actually the remnant of a major wartime brothel.

Storyville was New Orleans' historic red light district and hotbed of jazz music, sometimes referred to simply as "The District."

Children's literature inside, forest all around.

Popular tourist destination where witches in dark hats sell dried llama fetuses for good luck.