The Thornhill is a historic plantation in Forkland, Alabama. It was established in the early 1830s, covering over 2600 acres worth of land.

The centerpiece of the Thorntonhill Plantation is the main house built in 1833 by James Innes Thornton, a Virginia native, lawyer, and former politician. His family owned the Fall Hill plantation in Virginia and he moved to Greene County after he served as the Alabama?s third secretary of state from 1824 to 1834. He was also somehow related to George Washington by marriage.
Thortonhill functioned mostly as a cotton plantation. It had at least 156 slaves by 1860.

The main house at Thortonhill, designed by the highly esteemed William Nichols, was listed on the National Register of Historic Places in 1984. It is also a part of the Historic American Buildings Survey of 1934.