More than 30,000 gallons of water flow from Paradise Springs spring each hour—that’s 500 gallons of 47-degree water every minute, all year long. Now part of the Kettle Moraine State Forest—Southern Unit, the hidden gem in Eagle, Wis. was once owned by Louis J. Petit, a multimillionaire who made his fortune in the salt mining business. Petit’s grandson, budding beer baron August J. Pabst, inherited the property in 1932.

Most spring houses are built to simply protect the water source, but Petit built this elaborate structure with a wooden-and-copper dome roof and colorful fieldstone walls.