. Antique 1904 Monarch Keystone View Co. Stereoscope Viewer Manufactured by Monarch Keystone Company, Meadville, PA. Early 1900`s 3-D Stereoscope Viewing In Great Vintage Condition. Some Minor Issues But a Great Piece of Stereoscope History Almost 110 Years Ago ! Fascinating Functional Example and Conversation Piece From 1904. $90.00 or Best Offer 843-540-4032 No Text Messages Please .