Black Diamond Mines Regional Preserve

Stewartville was an unincorporated place in eastern Contra Costa County, California that is now a ghost town. It was located 6 miles (10 km) northeast of Mount Diablo, at an elevation of 558 feet (170 m). It was a mining town for the nearby coal mines.A post office operated at Stewartville from 1882 to 1902. The place was named for William Stewart, coal mine owner.

Somersville (also, Sommerville and Summerville) is an unincorporated ghost town in eastern Contra Costa County, California, United States. It is located 6 miles (10 km) north-northeast of Mount Diablo, at an elevation of 741 feet (226 m).Somersville was founded in the 1850s by gold miners. It was named after Francis Somers, who had discovered the Black Diamond Mine. Somersville was home to the Manhattan, Union, Eureka, Pittsburg and Independent mines. The town is no longer populated and is within the boundaries of the East Bay Regional Park District's Black Diamond Mines Regional Park. Somersville Road was named after the town; it is a major north–south arterial trunk road in the closest existing neighbor city, Antioch. Somersville's ruins have a fairly extensive number of graves in the Rose Hill Cemetery, many of which are those of miners who died in the coal mines. The cemetery was heavily vandalized prior to the East Bay Regional Park District taking it over in the 1970s. The Somersville mines are now sealed to prevent entry, due to frequent incidents of people becoming lost inside them during the mid 20th century.A post office operated at Somersville from 1863 to 1910.A reporter for the Antioch Ledger, May 7, 1870, described the town: "...Somersville has a four general merchandise stores, one drug store, one hotel, two large boarding houses, several minor ones, a doctor, barber, shoemaker, no tailor, four saloons, purs et simple, not counting liquors dispensed at groceries. As an offset, we have a flourishing Lodge of Good Templars and Sons of Temperance. Odd Fellows and Red Men each have an organization. A Protestant and a Catholic Church shed their humanizing influence around, both being well attended. The public school is maintained nearly all the year round, by a special tax when the State funds fails; from seventy-five to one hundred scholars is the average daily attendance. There are two departments, and two lady teachers, under whose painstaking auspices the fundamental branches flourish." In 1979, Somersville gained fame as the site of the largest historical archaeology excavation ever done in the U.S. at the time. Over 200 students from U.C Berkeley scraped and sifted through the eastern part of the townsite, recovering thousands of artifacts. The Public Broadcasting System examined the project in a 1980 episode of the anthropological documentary series Odyssey, titled "Other People's Garbage".

Nortonville is an unincorporated ghost town in Contra Costa County, California. It was located on Kirker Creek 5.5 miles (9 km) north-northeast of Mount Diablo, at an elevation of 801 feet (244 m).

West Hartley was an unincorporated community in eastern Contra Costa County, California. It was located 7 miles (11 km) northeast of Mount Diablo, at an elevation of 440 feet (134 m). It is now a ghost town. It was a mining town for the nearby coal mines.It was founded in the late 1880s and named for England's West Hartley coal mine.

Judsonville was a city in eastern Contra Costa County, California. It was located 3 miles (4.8 km) northeast of Stewartville. It was a mining town for the nearby coal mines.A post office operated at Judsonville from 1878 to 1883, with a closure in 1879. The name is in honor of Egbert Judson, part owner of a mine.

Suzanne Arlene "Suzie" Bombardier, (March 14, 1966 – June 22, 1980) was kidnapped, raped, and stabbed to death on June 22, 1980. On June 27, her body was found by a fisherman, floating in the San Joaquin River east of Antioch, California near its bridge, 60 miles (97 km) east of San Francisco. On December 11, 2017, after extensive DNA profiling, 63-year-old Mitchell Lynn Bacom, a convicted sex offender, was arrested as the prime suspect. He was charged with and convicted of kidnapping, rape, oral copulation, murder, and murder with use of a deadly weapon. This was Antioch's oldest cold case murder. At the time of Bombardier's homicide, Bacom was known to her family. Bombardier was raped, stabbed in the chest, and her heart was punctured. She was kidnapped from her sister's townhome in Antioch while she was babysitting her nieces. Her sister, Stephanie Mullen, arrived home at 4:00 a.m. to find Bombardier missing. Bombardier's father, Ted, said that she knew her killer, as there was no forced entry.

Somersville Towne Center is a regional shopping mall located in Antioch, California. Previously named County East Mall until 2004, the 501,259 square feet (46,570 m2) mall is managed by Urban Retail Properties. Originally opened in 1966, it is strategically positioned in one of the fastest growing areas of the San Francisco Bay Area, east Contra Costa County. Along with high population growth, east Contra Costa County is also experiencing sizable household income increases.Somersville Towne Center is the only enclosed regional shopping mall in east Contra Costa County and also the first such mall in the southeast portion of Antioch. The next closest shopping center of similar size and scale is The Streets of Brentwood open-air shopping center in nearby Brentwood, which opened in 2008. The mall is anchored by 24 Hour Fitness and Smart & Final.

Los Medanos College (LMC) is a public community college in Pittsburg, California. Established in 1974, LMC has an extension in Brentwood and is part of the Contra Costa Community College District.

Marsh Creek Springs was a private recreational facility in Contra Costa County, California. It was developed in 1927 by Gerald L. Gill on 90 acres alongside Marsh Creek. The facility included two swimming pools, wading pools, a livery stable, a dance hall and four baseball diamonds. By 1940 it had grown to cover 210 acres and was able to host 5,000 guests and 1,200 automobiles arriving from all over the Bay Area. In 1957 a flash flood sent a twelve-foot crest of water down Marsh Creek and destroyed the park. It was re-opened that same year but a second flood in 1962 again destroyed the park and it remained closed.

Sutter Delta Medical Center is a 145-bed general medical/surgical hospital in Antioch, California. A Level II Trauma Center, Sutter Delta is a not-for-profit teaching hospital and is ranked as a High Performing hospital for COPD and heart failure. It is part of Sutter Health. Originally founded as Antioch Hospital in 1927, it became Delta Memorial Hospital in the 1960s and joined Sutter Health in 1990. As of 2020, the CEO is Sherrie Hickman, who previously worked at Sutter Novato Community Hospital and in leadership roles at Kaiser Permanente and Dignity Health.

Angelo Quinto (March 10, 1990 – December 26, 2020) was a 30-year-old Filipino-American Navy veteran who died on December 26, 2020, from complications after being knelt on the neck by a police officer three days earlier. Prior to the encounter, police were responding to a call that Quinto was suffering from a mental health crisis. On February 18, 2021, Quinto's family and their lawyer, John Burris, filed a complaint against the Antioch Police Department.

Camp Stoneman was a United States Army facility located in Pittsburg, California. It served as a major troop staging area for and under the command of the San Francisco Port of Embarkation (SFPOE). The camp operated during World War II and the Korean War. The camp opened May 28, 1942 as a staging point for units deploying to the Pacific Ocean theater of World War II. The camp was named after George Stoneman, a cavalry commander during the American Civil War and Governor of California. It was decommissioned as a military post in 1954. The camp had a railroad track across the north side for receiving and shipping men. Late in the war the SFPOE experimented with embarking troops directly aboard a Liberty ship at the camp but that was not successful due to difficulties of large ship navigation to the camp. Next to the track, there were many buildings with loading docks, many of which were still there in 2017 along Bliss Avenue. There were seven barracks areas, each consisting of nine blocks (3 x 3) surrounding a mess hall. In addition to being a staging area for troops in transit, the Pacific Coast Transportation Corps Officer Training School was located at the camp. The camp also housed prisoners of war with the Italian Service Unit of the 18th Italian Quartermaster Service Company, which was based at the camp.