The Phelps Mansion, formerly known as The Monday Afternoon Clubhouse, is a three-story brick and stone mansion located on Court Street in Binghamton, New York. It was built in 1870 as the private home of Sherman D. Phelps. Mr. Phelps was a successful business man, banker, Republican elector for Abraham Lincoln, and mayor of the City of Binghamton. The building was designed by Isaac G. Perry who later became the chief architect for the New York State Capitol building in Albany, New York.
The mansion was purchased in 1905 by the Monday Afternoon Club. The club constructed a large ballroom on the back of the mansion in 1905 and continues to hold its weekly meetings there to this day. In 1986 ownership of the mansion was transferred to The Phelps Mansion Foundation.