The Farm is one of 8 Craft buildings in the game. The Farm has a 4x4 footprings and no build radius so you can line them up side by side.
Pro Tip: I dedicate my entire Highlands map to multiple farms and keep 10 each of Watermelon, Wheat, Potatoes and Squash ready for harvest since those seem to be the crops most used in quests that require more than an hour to ready for harvest.
