The world’s first penitentiary, meant to be humane, drove men insane.

Hundreds of glow-in-the-dark objects light up a museum in a historic zinc mine.

An enormous, inside-out glass globe built in 1935.

Eighteen miniature death-scene dioramas.

The world's longest known cave system.

This whimsical Oz-themed park had a wonderful impact on the surrounding neighborhood.

Enchanting gardens surround a derelict mansion, all hidden in plain sight behind a stone wall.

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.

A blend of art, antiquities, and Americana fill this museum, surrounded by whimsical, enchanting gardens.

Although built to generate electricity for Marylanders, this dam has become an all-you-can-eat buffet for American bald eagles.

A scenic fort on the harbor protected Philadelphia from an attack that never came.

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