Red Barns are buildings available on FarmVille. They can be bought from the market for 40,000 coins. They can also be used for storage. A Red Barn will increase a farmer's storage limit by 6.
As of January 8th, you can now upgrade barns. Individually for both upgrades, you must send out a request and get 10 neighbors to help each time. The first upgrade results in 11 storage; the second upgrade results in 18 storage. You can also pay 10 cash for the next available upgrade and get it immediately. Upgrades can be performed on any storage buildings, chicken coops, and dairy farms, with the latter two coming soon. (non-rotatable)
A fully upgraded red barn can hold 32 items while taking up 48 spaces. This is considerably less efficient than a fully upgraded tool shed.