John Rains, a former soldier, married the wealthy Maria Merced Williams after he arrived in California as a cattle and sheep driver in 1847. The couple purchased the 13,000 acre Rancho de Cucamonga. In 1860, they commissioned the building of the Rains House by Ohio brick masons who utilized bricks made by Joseph Mullaly from the red clay on the site. Its flat roof was waterproofed by tar from the brea pits in Los Angeles. An open flume carried water from springs through the kitchen, into the patio, and under the house to the orchard, thereby providing cooling for the structure. The original house had an entry hall, a parlor, and three bedrooms in the front, with a patio area flanked by a dining room, a kitchen, a padré’s room, and two guest rooms.