Clyde, California

Rancho Monte del Diablo (Devil's Mount Ranch in Spanish) was a 17,921-acre (72.52 km2) Mexican land grant in present-day Contra Costa County, California given in 1834 by Governor José Figueroa to Salvio Pacheco. The name "Monte del Diablo" means "thicket of the devil" in Spanish. The name was later incorrectly translated as Mount Diablo. The grant covered the area from the Walnut Creek channel east to the hills, and generally from the Mount Diablo foothills north along Lime Ridge to Avon on the Carquinez Strait of the Sacramento River, and included present day Concord and parts of Pleasant Hill. Pacheco and Clayton are outside of the Rancho Monte del Diablo grant.

Port Chicago was a town on the southern banks of Suisun Bay, in Contra Costa County, California. It was located 6.5 miles (10 km) east-northeast of Martinez, at an elevation of 13 feet (4 m). It is best known as the site of a devastating explosion at its Naval Munitions Depot during World War II.

North Concord/Martinez station is a Bay Area Rapid Transit (BART) station located in the Sun Terrace neighborhood of Concord, California. The station serves the northern area of Concord and nearby Martinez. It is located near State Route 4.

GoMentum Station is a testing ground for connected and autonomous vehicles at the former Concord Naval Weapons Station (CNWS) in Concord, California, United States. The property was acquired and repurposed by the Contra Costa Transportation Authority, acquired in August 2018 by AAA Northern California, Nevada & Utah.In October 2014, the Contra Costa Transportation Authority announced that the GoMentum Station proving grounds would be used to test self-driving cars; according to them, "The public will not have access to the test site, and the self-driving cars will be restricted to the test bed site. With 2,100 acres (850 ha) of testing area and 19.6 miles (31.5 km) of paved roadway, the CNWS is currently the largest secure test bed site in the United States". Mercedes-Benz is reported to have licenses to test new driving technology, including smart infrastructure such as traffic signals that communicate with cars. Among the site's other notable features: "a 7-mile (11 km)-long roadway is great for testing high-speed driving, and a pair of 1,400-foot (430 m)-long tunnels" for sensor testing.Among the roughly 30 partners listed on the company's site are automakers Toyota and Honda, ridesharing companies Uber and Lyft and China-based autonomous driving company Baidu. In summer 2015, reports suggested the Apple electric car project was interested in using the site, as members of Apple's Special Project group were reported to have met GoMentum representatives but there were no subsequent reports of Apple personnel and vehicles actually using the site.In August 2019, GoMentum announced the October launch of its V2X (vehicles-to-everything) testing facility.

KVHS (90.5 FM, "90.5 The Edge") is a non-profit high school radio station playing an active rock music format. It is licensed to the Mt. Diablo Unified School District and broadcasts from the campus of Clayton Valley Charter High School, Concord, California. The signal reaches the counties of Contra Costa, Solano, Napa, San Joaquin, West Sacramento and Yolo, and KVHS primarily serves the Diablo Valley area.

The Port Chicago disaster was a deadly munitions explosion of the ship SS E. A. Bryan on July 17, 1944, at the Port Chicago Naval Magazine in Port Chicago, California, United States. Munitions while being loaded onto a cargo vessel bound for the Pacific Theater of Operations, detonated killing 320 sailors and civilians and injuring 390 others. Two-thirds of the dead and injured were enlisted African American sailors. A month later, the unsafe conditions prompted hundreds of servicemen to refuse to load munitions, an act known as the Port Chicago Mutiny. Fifty men‍—‌called the "Port Chicago 50"‍—‌were convicted of mutiny and sentenced to 15 years of prison and hard labor, as well as a dishonorable discharge. Forty-seven of the 50 were released in January 1946; the remaining three served additional months in prison. During and after the mutiny court-martial, questions were raised about the fairness and legality of the proceedings. Owing to public pressure, the United States Navy reconvened the courts-martial board in 1945—that board re-affirmed convictions. Widespread publicity surrounding the case turned it into a cause célèbre among Americans opposing discrimination targeting African Americans; it and other race-related Navy protests of 1944–45 led the Navy to change its practices and initiate the desegregation of its forces beginning in February 1946. In 1994, the Port Chicago Naval Magazine National Memorial was dedicated to the lives lost in the disaster.

The Port Chicago Naval Magazine National Memorial is a memorial dedicated in 1994 recognizing the dead of the Port Chicago disaster, and the critical role played by Port Chicago, California during World War II, in serving as the main facility for the Pacific Theater of Operations. The national memorial is located at the Concord Naval Weapons Station near Concord, California, in the United States. The 1944 Port Chicago disaster occurred at the naval magazine and resulted in the largest domestic loss of life during World War II. A total of 320 sailors and civilians were instantly killed on July 17, 1944, when the ships they were loading with ammunition and bombs exploded. The majority of the deaths were African American sailors working for the racially segregated military. The explosion and its aftermath led to the largest Naval mutiny in US history, and it and the subsequent trial became major catalysts for the United States Navy to desegregate following the war.

The Don Fernando Pacheco Adobe is located at 3119 Grant Street in Concord, California.The Fernando Pacheco Adobe is the only Concord landmark listed in all three Historical Registries: entry on the National Register occurred on June 6, 1980; the California Registered landmark number is 455; and the Concord Historical Landmark designation is 1-26-26/5458. The Adobe was built by Don Fernando in the early 1850s as the base of operations for his growing ranch activities, and as his family's formal residence. Fernando was the oldest son of Don Salvio Pacheco. He was born on May 30, 1818, while his father was assigned to a Militia-Guard unit at the Pueblo of San Jose. At age 17, he was sent to take possession and mark the boundaries of his father's 17,921 acre land grant. Fernando was given 1,500 acres as initial share of the rancho. He subsequently married Pasquala (Figeroa) (Juarez) – a widow. Their six children: Pedro, Bonifacio, Cipriana, Maria Asuncion (who married Jose Julian Cantua), Librada and Bersabe were raised at the Adobe. Don Fernando's family enjoyed a reputation as gracious hosts. They were famous for their generosity and extensive fiestas on Adobe's then lush, well irrigated grounds. The Adobe's 32” thick walls were built of local adobe – mud. Ownership remained with Don Fernando's descendants until 1918. The land and adobe were then sold to the California Water Service Company ; it then was essentially abandoned. In 1940 title to 2 and 1/2 acres and the deteriorated adobe structure transferred to Contra Cost County, which leased it to the Horsemen's Association. The Horsemen undertook a major rehabilitation, and used the then remote facility and corral for their headquarters. In 1979, the country transferred the Adobe and its grounds to its current owner, the City of Concord. In the early 1980s the Horsemen, the city, and the Concord Historical Society completed another restoration effort to stabilize the landmark Adobe. The Horsemen's Association continues activities on site. The Fernando Pacheco Adobe is located at 3119 Grant Street, now well within the city limits. It is adjacent to Hillcrest Park and the De Anza Expedition Memorial marker.

Matteo's Dream is an all-abilities playground in an urban park in Concord, California. It opened on May 16, 2007. Matteo Henderson was a boy with serious disabilities including blindness, cerebral palsy, and cognitive development. He used a wheelchair for transportation. The playground was built with US$770,000 of donated materials and with the labor of 1600 volunteers. Matteo, and many other children of all abilities have enjoyed the playground. Persons with disabilities are able to drive their wheelchairs directly onto the structure. Features of the playground are specially engineered to accommodate people with various disabilities. Matteo died on March 16, 2011, at the age of 11. In January 2014, a Matteo's Dream themed Rose Parade float was featured in the 125th Rose Parade in Pasadena, California.

Seal Islands are a pair of islands in Suisun Bay at the mouth of the Sacramento-San Joaquin River Delta in Contra Costa County, California, 10 km east of Benicia, and 500 metres off-shore from the former Concord Naval Weapons Station and Port Chicago Naval Magazine.

Grayson Creek is a stream in Contra Costa County in northern California that flows northeasterly 7.4 miles (11.9 km) from its origin in Briones Regional Park to Pacheco Slough four miles east of Martinez. Pacheco Slough, in turn, connects to Suisun Bay. The Grayson Creek subwatershed is part of the Walnut Creek watershed and includes the cities of Pleasant Hill and Pacheco, California. Murderer's (aka Murderous) Creek is a seasonal drainage creek also located in Pleasant Hill. Murderous Creek was named when the surveyors found a victim hanging from a tree near the stream in 1849. Today, large portions of the Creek have disappeared, but it can be found meandering through several residential subdivisions below the hillside near Pleasant Hill Road and Withers Avenue. The portion of Murderer's Creek that remains is being heavily surcharged and overburdened by the discharge of runoff water into the Creek from County roads and from upslope private developments, and the riparian property owners are experiencing extensive erosion and subsidence issues.

The Walnut Creek mainstem is a 12.3-mile-long (19.8-kilometer) northward-flowing stream in northern California. The Walnut Creek watershed lies in central Contra Costa County, California and drains the west side of Mount Diablo and the east side of the East Bay Hills. The Walnut Creek mainstem is now mostly a concrete or earthen flood control channel until it reaches Pacheco Creek on its way to Suisun Bay. Walnut Creek was named for the abundant native Northern California walnut trees (Juglans hindsii) which lined its banks historically. The city of Walnut Creek, California was named for the creek when its post office was established in the 1860s.