The Town of Carmel Historical Society, founded in 1977, is a nonprofit organization chartered by the New York State Education Department Board of Regents. Its mission statement addresses the preservation of local history and informing the community of our past.

It is an all-volunteer service organization managed by a Board of four officers and twelve trustees. Memberships support the operating budget.

The Society operates and partly maintains the Historical Center in the old Town Hall at 40 McAlpin Avenue in Mahopac's "old village". The hall, built in 1902, was originally a community center. It had a stage which was used for theatrical productions; when town meetings were held, the board members sat on the stage. Later renovations were made to form town offices.

The building was deeded to the Town on October 17, 1904 by Edwin A. McAlpin and his wife Annie. General McAlpin was the developer of what was then the "new village", known as McAlpin Square.