Welcome to Putnam County, NY: Stone Chamber capitol of the world. Here in New York and New England, we have these odd little stone buildings that are something of an enigma. They dot the landscape and number in the hundreds. Nobody knows their age, origin, or purpose and speculations range from Colonial root cellars to ancient Celtic temples.
I personally believe they are of Celtic origin. If you would like to know why, please visit my website: http://www.kelticenergy.org