The amphitheater at Old Mill Park is located behind the public library, which is located at 375 Throckmorton Ave., Mill Valley, CA 94941. The Outdoor Art Club is a half-mile walk away, so you might want spare pair of shoes!
A walking map between the two locations can be found here.
A casual drop-in post-wedding brunch, starting around 10 and ending around 4—stop by and say goodbye before you go! Please note there is a 13 car limit at the Spirit House, so please sign up for a spot here, and coordinate carpools amongst yourselves! If carpooling is not an option, Ubering should be! You can even park in Woodacre or Fairfax and grab an Uber from there.