A combined around 100,000 acres were listed for sale in Fauquier County recently; the value of all Fauquier County farmsand rural real estate for sale was around $332 million. Fauquier County ranks 24th based on the combined acreage of land for sale among all the counties in the Old Dominion. Warrenton had the most land for sale. Fauquier County is one of the ten biggest counties in Virginia (651 square miles). It's located in the Northern Virginia region of Virginia.