The former Hancock County Jail is a structure built in 1886 that functioned as an incarceration facility for the County, and a residence for the Sheriff or jail keeper's family. The Queen Anne style building with Renaissance Revival details was designed by the Portland architect Francis H. Fassett, and was used to house inmates through the mid-1970s. The front half of the facility is a comfortable residence, featuring period detailing, while the back half contains fourteen small granite cells on two levels. Small openings in the dividing wall between the two sections allowed the jailer to monitor the prisoners or pass provisions from the kitchen to the inmates. Currently the former Hancock County Jail is the home of the Ellsworth Historical Society. This property was entered in National Register of Historic Places as a good example of a building designed to serve both domestic and penal functions, and for its long association with the governmental functions of Hancock County.