Abandoned Missile Silo, Willsboro, NY

Site 4 of the 556th Strategic Missile Squadron, Plattsburgh. One of 12 Atlas F ICBM sites in NY and VT which ringed Plattsburgh Air Force Base during the Cold War. The silos were 174 feet deep and 54 feet in diameter.

See also:

http://www.atlasmissilesilo.com/556thSMS.htm
http://asuwlink.uwyo.edu/~jimkirk/atlas.html
http://www.killerjeanne.com/
http://www.clui.org/clui_4_1/lotl/00f/00f7a.html