The Phillips Mansion in Pomona, California, is one of the last surviving remnants of Spadra, a 19th-century frontier town that has largely disappeared. Built in 1875 in the Second-Empire style, the brick home has withstood earthquakes, avoided demolition and undergone multiple renovations over its 150-year history. Today, it stands in an industrial area as a designated historical landmark.

The mansion was commissioned by Louis Phillips, a Jewish immigrant from Poland who arrived in the United States in 1848 and later became a prosperous rancher and real estate investor. At his peak, Phillips owned tens of thousands of acres of land, thousands of sheep and hundreds of cattle. He played a central role in developing Spadra by selling land to settlers and persuading the Southern Pacific Railroad to establish a stop there, helping the town grow to about 500 residents.

Although Spadra declined after the railroad stop was moved to Colton in 1883, Phillips continued to shape the region, including serving as a founder and trustee of Pomona College. After his death in 1900 and his wife Esther's death in 1918, the mansion eventually fell into disuse and faced demolition.

In 1974, the Historical Society of Pomona Valley purchased and restored the home, securing its place on the National Registry of Historic Places. The organization now offers occasional tours of the mansion and nearby Spadra Cemetery, where Phillips is buried, marking the final physical traces of the once-thriving town.