Dunsmuir Open Space is a small East Bay hills preserve with a few mostly unmapped very steep trails. The neighboring large historic Dunsmuir-Hellman, founded in 1878, contains the grandiose victorian mansion built in 1899 by Alexander Dunsmuir, son of Robert Dunsmuir, a wealthy coal magnate from Victoria, BC, as a wedding gift to his wife. Unfortunately he died on their honeymoon, and she died in the house two years later. Bought and occupied by the Hellman family for over 50 years it now serves as a wedding and conference events space. en.wikipedia.org/wiki/Dunsmuir_House