The Casa de Rancho Cucamonga, commonly known as the John Rains House, is a historic house located at 8810 Hemlock St. in Rancho Cucamonga, California. The house was built in 1860–1861 after John Rains purchased the Rancho Cucamonga land grant in 1858 from the Tapia estate. The brick house featured its own cooling system, which used ducts to send creek water under the house. John Rains was a prominent businessman and socialite who opened California's first commercial winery, and his house hosted lavish parties for other local elites. Rains' fortunes soon took a turn for the worse, though; he had to mortgage the house after several business failings, and in 1862 he was murdered. Maria Merced Williams, Rains' wife, who had originally inherited the property from her father, attempted to regain