Diablo Foothills Regional Park

Castle Rock Regional Recreation Area is a 18,000 acres (73 km2) regional park of the East Bay Regional Park District. It is located in Contra Costa County, in the East Bay region of northern California.

The Old Borges Ranch is a 1,035 acres (419 ha) historic district in the Mt. Diablo foothills within the 2,600-acre (1,100 ha) Walnut Creek Open Space in Contra Costa County, California. A former cattle ranch, Old Borges Ranch includes multiple historic buildings, a ranger station, farm animals, and access to trails.

Rancho San Ramon (St. Raymond Ranch in Spanish) was a 8,917-acre (36.09 km2) Mexican land grant in the northern San Ramon Valley of present-day Contra Costa County, California. Rancho San Ramon (Amador) was adjacent in the southern San Ramon Valley. It was given in 1833 by Governor Jose Figueroa to Mariano Castro and Bartolome Pacheco. Governor Figueroa granted Castro and Pacheco two square leagues of San Ramon Valley from the crest of the western ridge to the crest of the east. Castro had the northern square league, and Pacheco the southern.The grant included present-day Alamo, Danville and northern San Ramon.

California's 11th congressional district is a congressional district in the U.S. state of California and is represented by Nancy Pelosi. Before redistricting, the 11th district consisted of most of Contra Costa County. Mark DeSaulnier, a Democrat, represented the district from January 2015 to January 2023. Cities and CDPs in the district included Alamo, Bay Point, Blackhawk, Clayton, Concord, Diablo, El Cerrito, El Sobrante, Kensington, Lafayette, Moraga, Orinda, Pinole, Pittsburg, Pleasant Hill, San Pablo, Richmond, and Walnut Creek; most of Danville; and parts of Antioch and Martinez.Following redistricting in 2023 by the California Citizens Redistricting Commission, the 11th district is entirely in San Francisco, and includes most of the city with the exception of the Excelsior District, Visitacion Valley, Portola, and Ocean View on the city's southern edge. Former Speaker of the House Nancy Pelosi represents the new 11th district.

Area code 925 is a telephone area code in the North American Numbering Plan for a northern part of the U.S. state of California. It was created in an area code split of area code 510 in 1998. The numbering plan area comprises the inland portions of the East Bay counties of Alameda and Contra Costa.

The Tassajara Formation is a geologic unit within the Livermore Valley of Northern California, United States. The formation surfaces only in the northern upland parts of the Livermore Valley and underlie the central part of the valley floor at a depth ranging from 250 feet (80 m) to 700 feet (200 m). The Tassajara Formation consists of sediments ranging from brown to gray mudstone, andesitic sandstone, conglomerate, and minor bentonitic and pumiceous tuff. In the northern San Ramon area, the Tassajara Formation underlies Quaternary valley fill material. The Bishop Subbasin is an aquifer that resides between two subsurface ridge formations of the Tassajara Formation in the northern extremity of the Amador Valley.

North Gate is a census-designated place in Contra Costa County, California. North Gate sits at an elevation of 253 feet (77 m). The 2010 United States census reported North Gate's population was 679.

Northgate High School (NHS) is a public high school located in the suburban Northgate neighborhood of Walnut Creek, California, United States. The most recent of five high schools in the Mount Diablo Unified School District, the school was built in 1974, and is home to approximately 1,500 students from Walnut Creek and Concord, California, grades 9–12. Its name derives from its location at the north entrance of Mount Diablo State Park.

San Miguel is a census-designated place in Contra Costa County, California. San Miguel sits at an elevation of 249 feet (76 m). The 2010 United States census reported San Miguel's population was 3,392.

Monte Vista High School is a comprehensive public high school located in Danville, California, United States. It is a National Blue Ribbon school, as well as a California Distinguished School. It is fully WASC accredited. The school is located in the San Ramon Valley, approximately 35 miles (56 km) east of San Francisco, and is part of the San Ramon Valley Unified School District. Their school mascot is a mustang.

Rancho Arroyo de Las Nueces y Bolbones (also called "San Miguel") was a 17,782-acre (71.96 km2) Mexican land grant in present-day Contra Costa County, California given in 1834 by Governor José Figueroa to Juana Sanchez de Pacheco.The grant was named after the principal waterway, Arroyo de las Nueces (Walnut Creek), and for the local group of indigenous Americans (known as Bolbones in Spanish, also known as Volvon). The grant was on the western slope of Mount Diablo and includes the area of the present-day city of Walnut Creek. Approximately a quarter of the original rancho has been protected since the early 20th century within the boundaries of Mt. Diablo State Park.

Shell Ridge is a census-designated place in Contra Costa County, California, United States. Shell Ridge sits at an elevation of 295 feet (90 m). The 2010 United States census reported Shell Ridge's population was 959.