Castella is a small, unincorporated community and census-designated place in the upper Sacramento Canyon of Shasta County, California. It is located 46 miles north of Redding on Interstate 5, and is home to Castle Crags State Park. Its population is 214 as of the 2020 census. It has a Chevron gas station/store and a post office. The ZIP Code is 96017. The community is inside area code 530.