A four-alarm fire has destroyed a Santa Rosa landmark, the Huntington House. The home, on the city's one-time Millionaires Row, was unoccupied and no injuries were reported, fire officials said. The blaze apparently started in the basement of the house, built in the 1850s, then rapidly spread up the walls and into the attic, Battalion Chief Carl Goodson said. The pre-Victorian house on Mendocino Avenue was being considered for designation as a historical landmark by both the city and the state. Goodson said cause of the fire was not known.