Castle Hills is a city located in Bexar County, Texas, USA. Castle Hills is an enclave of San Antonio and is part of the San Antonio Metropolitan Statistical Area. It is bisected into a northern and southern half by interstate highway loop I-410.
It is located at the southern end of Northwest Military Highway, the northern end being located at U.S. Army Camp Bullis. According to the Köppen Climate Classification system, Castle Hills has a humid subtropical climate.