Just below the 5.10b crux of "The Great Roof"
The Great Roof is a fun 5.10b on the south face of Goat Rock that ascends up the obvious large overhang. Though not terribly difficult, the crux move requires some nerve as you are suspended above a big gap of air, and falling will cause you to swing in a huge arc on the top rope. Other than the crux, it is mostly a 5.7 to 5.8. For the most part, a beginner could climb it, with the exception of the crux.
Follow the directions to Goat Rock on the main page.
Once on top, head along the summit "ridge" to the south. This will bring you over the actual highpoint of the rock, and down about 7 feet to a small ledge where there are three good bolts. Here you can anchor in your top rope and make the fun rappell down to the bottom.
From the bottom, just head up the crack system that follows the line of the top rope. The lower section of the route is about 5.8 and pretty strait-forward. It is when you approach the cave below the roof where things get interesting. You are already under the overhang here, and falling will cause you to swing out a great deal. To get into the cave, you should head right and go up anyway you see fit. You might have to hoist yourself into the cave itself. Once in the cave, the crux is just above you, just where the rope comes over the overhang. With awkward holds, climb "backwards" and out towards the point where the toprope comes over the lip. Once nearly out of the cave, throw big for a jug to your upper right, above the cave roof. Once you get past this, it is an easy 5.7 to the top.
You'll need a few full-length slings, 60 meter rope, and a few locking carabiners to clip into the bolts. A helmet is strongly recommended for this route, seeing that falling here means a big swing, sending you flying back into the rock. Water, sunscreen, camera, and anything else you want.