From the plaque:
In 1839 Governor Juan Alvarado
granted the 13,000-acre tract called Cucamonga to Tiburcio
Tapia, an ex-soldier who was a prominent merchant and
alcalde in Los Angeles. A half mile west of this marker
Tapia, employing Indian laborers, immediately built an
adobe house on a vantage point on Red Hill. The large
adobe was abandoned in 1858 when Tapia's heirs sold the
rancho. The adobe soon disintegrated into its native earth.
This marker is located on land which once was a part of
Plaque placed by the State Department of Parks and Recreation in cooperation with E Clampus Vitus-Billy Holcomb Chapter, Rancho Cucamonga Historical Society, San Bernardino Co. Museum Association, and Thomas Vineyards, June 2, 1985.