The New London County Courthouse is a historic courthouse located at 70 Huntington Street at the top of State Street in New London, Connecticut. It was built in 1784-86, and its design is attributed to Isaac Fitch. An addition constructed in 1909 was designed by Dudley St. Clair Donnelly.According to a plaque on the building, the New London County Courthouse is oldest courthouse in Connecticut. The State of Connecticut Superior Court sits there. It was added to the National Register of Historic Places in 1970.