Castroville, the "little Alsace" of Texas, is located on the Medina River and U.S. Highway 90 twenty-five miles west of San Antonio in eastern Medina County. The town was named for its founder, Henri Castro, with whom the Republic of Texas negotiated an empresario contract on January 15, 1842. Castro's grant began four miles west of the Medina River and comprised frontier lands in Comanche territory. Wanting to locate his first settlement on the Medina River, Castro purchased the sixteen leagues between his grant and the river from John McMullen of San Antonio.