The history of this trail runs vast and deep. It's been touted as one of the very first downhill race courses. Luckily it's still around and open for the rest of us to enjoy. Of course, there are plenty of gnarlier, more technical choices throughout the area to ride. At the very least, you should treat this trail as a piece of history, and reverence should be paid to all those initial pioneers who rode in on their "Klunkers" and jump started the sport of mountain biking.
As for the trail itself, it's essentially winding doubletrack that's officially called Cascade Canyon Road that heads from a neighborhood in Fairfax at its base to an intersection at San Geronimo Ridge Road
at the top. It's a straightforward descent of ~1300 feet with many iconic waypoints
as defined by the initial crew who raced it.
To get to the top, you can either ride straight up the beast or ascend via Pine Mountain Road off Bolinas Road to the south. From the top, you'll pedal out on a bit of a plateau before reaching the official downhill start point which just keeps going down and down and down.
Start at the top, end at the bottom, go as fast as you can!