Hacienda Heights is an unincorporated community in the eastern San Gabriel Valley of Los Angeles County, California, set against the western flank of the Puente Hills. Home to roughly 54,000 residents, it occupies about 11 square miles of flatland neighborhoods and rising hillside terrain that separates the San Gabriel Valley from the Whittier area and the inland Los Angeles basin. Because it is unincorporated, Hacienda Heights is governed directly by Los Angeles County rather than its own city government. The community developed largely in the decades after World War II, when the flatlands and lower slopes were built out with suburban tract housing to accommodate the region's postwar growth. The result is a mature, low-rise suburb of single-family homes, schools, and shopping centers, with denser commercial corridors along its main boulevards and quieter cul-de-sac streets in the hills. The hillside reaches offer views across the valley and, in many places, direct access to the preserved open space of the Puente Hills. Today Hacienda Heights is among the more populous unincorporated places in Los Angeles County, and its roughly 17,000 housing units are overwhelmingly single-family residences. Hacienda Heights is perhaps best known for the Hsi Lai Temple, a striking Chinese Buddhist monastery set into the foothills that serves as the North American regional headquarters of the Fo Guang Shan order. The temple is both a working religious center and a widely visited cultural landmark, and its presence reflects the community's diversity—a defining feature of the modern San Gabriel Valley. Hacienda Heights' combination of hillside setting, mature suburban fabric, and location at the crossroads of the San Gabriel Valley gives it a distinct character among Los Angeles County's many unincorporated communities, appealing to families and commuters who want a foothill backdrop without leaving the metropolitan core.