Sibley Volcanic Regional Preserve, managed by the East Bay Regional Parks District. Also in the park are other small volcanos, with 2 quarry pits from former mining operations exposing the inner layers of the volcano.
The true summit is unclear, as an apparently manmade pile of rocks may be the current highest point on the broad summit plateau. However, this is one of those peaks where standing on the true summit shouldn't be much of a priority. While much of the summit is closed due to private antenna operations, and tall trees block most views, better views can be had if you walk around the outside of the fences on the Northeast side of the summit.
Getting ThereWith advances in internet technology, rather than write out various complicated directions, here is the link via Google
Once at the entrance, follow the fire road north. Here is a map of the park.
Red TapeNothing out of the ordinary for a Regional Park
External LinksOfficial Sibley Website
Google Maps from Oakland Airport
Official Sibley Map
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