Text from the Farmington web site (9/26/16):
Built for John and Lucy Speed, Farmington was completed in 1816. The Historic Home was the center of a thriving 550 acre hemp plantation that was sustained by nearly 60 enslaved African Americans who lived in cabins on the propery. In the summer of 1841, Abraham Lincoln visited Farmington for three weeks. Relationships he formed with member of the Speed family, including his future Attorney General James Speed, became important during Lincoln’s Presidency and the Civil War.
There is circumstantial evidence that the plans for Farmington were taken from a plan by Thomas Jefferson. We know Lucy’s family had close connections with Jefferson, and we know that Farmington’s floor plan is very similar to one drawn by Jefferson. The building contract for Farmington mentions Paul Skidmore as having done the plan for the house. Whether Skidmore was provided with a sketch from Jefferson or a verbal description from Lucy of what she envisioned or whether he independently arrived at the original design, we will never know. In any event, construction, much of it undoubtedly by slaves, began in 1815 and was completed by 1816.