The King William area was originally farmland, irrigated by acequias flowing from the San Antonio River, owned by the 1718 Mission San Antonio de Valero (known as the Alamo). By the beginning of the 19th century, the missions were fully secularized, and the land belonging to Mission Concepcion was bought, sold, and divided into tracts by land speculators, beginning in the 1840s.
One of the earliest to settle was Carl Guenther, a German immigrant who built Pioneer Flour Mills on the lower bend of the San Antonio River. A number of other successful and influential German immigrants discovered the area and began building mansions, using Greek Revival, Victorian, and Italianate architectural styles. Ernst Altgelt, the first to build on current-day King William Street, is credited with naming his street after King Wilhelm I of Prussia.
When neighborhoods to the north began drawing King William residents away in the 1920s, many of the grand mansions were turned into apartments and the district fell into decline. But in the 1960s, creative young professionals rediscovered King William and began a renaissance, which continues to this day. The district was expanded in 1984 to include a more eclectic neighborhood of cottages south of Alamo Street.