A Barn is a High Soak Specialized Building with 1x floor of 34x24 (816x tiles total) which is sometimes used to house Domesticated Animals, however, Domestic Animals inside a Barn will NOT mate. For this reason Barns are generally not recommend to build or use. To Wrangle a Domesticated Animal into a Barn use a Lasso or a Rope. Inside a Barn is the only place the Internal Wall, Barn Stall, can be built, used to separate and manage Domesticated Animals. A Food Trough cannot be built inside a Barn, but can be built outside and then brought in.
Specialized Buildings are buildings which generally must be built on Pavement and can be entered and but don't always not count as "inside". Generally these buildings can be Locked.