The Greene County Courthouse, located in Jefferson, Iowa, United States, was built in 1918. It was individually listed on the National Register of Historic Places in 1978 as a part of the County Courthouses in Iowa Thematic Resource. In 2011, it was included as a contributing property in the Jefferson Square Commercial Historic District. The courthouse is the third structure to house court functions and county administration. The courthouse features the Mahany Tower, a 120 feet bell tower.