Marin County is located in the northwestern part of the San Francisco Bay Area of the U.S. state of California. As of the 2010 census, the population was 252,409. Its county seat is San Rafael. Marin County is across the Golden Gate Bridge from San Francisco, and is included in the San Francisco–Oakland–Berkeley, CA Metropolitan Statistical Area. As of 2019, Marin County had the sixth highest income per capita of all U.S. counties, at $141,735. The county is governed by the Marin County Board of Supervisors. San Quentin State Prison is located in the county, as is George Lucas' Skywalker Ranch. Autodesk, the publisher of AutoCAD, is also headquartered there, as well as numerous other high-tech companies. The Marin County Civic Center was designed by Frank Lloyd Wright and draws thousands of visitors a year to guided tours of its arch and atrium design. In 1994, a new county jail facility was embedded into the hillside nearby. Marin County's natural sites include the Muir Woods redwood forest, the Marin Headlands, Stinson Beach, the Point Reyes National Seashore, and Mount Tamalpais. The United States' oldest cross country running event, the Dipsea Race, takes place annually in Marin County, attracting thousands of athletes. Mountain biking was invented on the slopes of Mount Tamalpais in Marin.

Novato ( nə-VAH-toh) is a city in northern Marin County, in the North Bay region of the San Francisco Bay Area, in the U.S. state of California. At the 2010 census, its population was 51,904. Novato is located about 10 miles (16 km) northwest of San Rafael and about 30 miles (48 km) north of San Francisco on U.S. 101. Novato has been called one of the best places to live in the U.S.

Petaluma (; Coast Miwok: Péta Lúuma) is a city in Sonoma County, part of the North Bay sub-region of the San Francisco Bay Area, located 37 mi (60 km) north of San Francisco. Its population was 57,941 according to the 2010 Census.The Rancho Petaluma Adobe, located in Petaluma, is a National Historic Landmark. Construction began in 1836 by order of General Mariano Guadalupe Vallejo, who was then the Commandant of the San Francisco Presidio. It was the center of a 66,000-acre (270 km2) ranch stretching from Petaluma River to Sonoma Creek. The adobe is considered one of the best-preserved buildings of its era in Northern California. Other historical buildings include the Washoe House, built in 1859, and the Petaluma Creamery, established in 1903, which marked Petaluma as an agricultural center for eggs and dairy. The name comes from the Coast Miwok name Péta Lúuma (lit. 'hill backside'), a village once located near the present-day city borders. Petaluma has a well-preserved, historic city center which includes many buildings that survived the 1906 San Francisco earthquake.

Sonoma is a city in Sonoma County, California in Sonoma Valley. Known as a part of Wine Country in the Sonoma Valley AVA Appellation, Sonoma is the home of the Sonoma International Film Festival and a historic town plaza, a remnant of the town's Mexican colonial past. Sonoma's population was 10,648 as of the 2010 census, while the Sonoma urban area had a population of 32,678.