Monticello is a city in Jefferson County, Florida, United States. The population was 2,533 at the 2000 census. As of 2004, the population recorded by the U.S. Census Bureau is 2,572. It is the county seat of Jefferson County. The city is named after Monticello, the estate of the county's namesake, Thomas Jefferson, on which the county courthouse was modeled.Monticello is home to Indian mounds and many historic buildings, including the Perkins Opera House and Monticello Old Jail Museum.