Bay seniors hurtling down 280 barely spare a glance at dreamy, bucolic Crystal Springs in San Mateo. It is a wonder but not a natural one, a reservoir (actually two of them) with a 15 mile trail around and above them. Portola camped here in 1795 but the site is now under water. There are a series of trails that lead you past Filoli, the Phleger Estate and the elegant little Pulgas Water Temple. Does any Peninsula Geezer out there know why it is named for the Spanish word for “fleas’?