Contra Costa County is a county located in the U.S. state of California, in the East Bay of the San Francisco Bay Area. ▻ Focused and ambitious actions are taken to reduce greenhouse gas emissions, improve community resilience, and adapt equitably to a changing climate.This is the ranch home of John Muir, 1838-1914, explorer, naturalist, author and foremost advocate of forest protection and of national parks. This three-story administration building and outdoor plaza is more than a construction achievement; it's a community revitalization effort. Contra Costa County administrators did not say when demolition of the 12story building, one of the tallest in the county, might begin.