Getting There.

Briones is located in the East Bay, in the middle of Contra Costa County, located between the cities of Lafayette, Walnut Creek, Pleasant Hill, Concord, and Martinez.

There are 5 entrances to Briones.

• Lafayette Ridge Staging Area
• Alhambra Creek Staging Area
  (Parking fee charged area on weekends)
• Briones Rd At Alhambra Valley Rd
• Bear Creek Staging Area - exit Highway 24 at Happy Valley Road and go north. Turn right at Bear Creek Road and drive a short distance to the staging area (on the right).
  (Parking fee charged area on weekends)
• Gloria Terrace

You can view more information from the official site.

Briones is the red outlined green blob on the right.

Here is its location realtive to the surrounding towns. I live in Pleasant Hill.

Here is an overview map of the park. You can also grab the high res PDF map.

Here are some additional links.

http://www.bahiker.com/eastbayhikes/briones.html

http://www.coloniapress.com/hikes_trips.html

http://www.mtbreview.com/trails/California-BayArea/BrionesStatePark.html