Four miles north of the 210 freeway in Altadena, the Cobb Estate sits at the top of Lake Avenue at the corner of Loma Alta Drive. If you want a quick commune with nature after work, take the half-mile loop around the grounds, filled with eucalyptus, pepper and acacia trees, wild buckwheat and mustard. Your leashed dog is welcome. Enter through the historic wrought-iron gates and ascend the winding paved driveway to the site of what was once one of Altadena's premier mansions, built in 1916 by lumber magnate Charles H. Cobb. The Marx Brothers bought the 107-acre tract in 1960 and planned to sell it for use as a cemetery, but local ecologists stepped in and turned it over to the Forest Service in 1971. There are several side trails you can explore, including a couple that lead down into Las Flores Canyon, a waterfall and abandoned gold mines. If you are more ambitious, take the Sam Merrill Trail to the top of Echo Mountain, 2.5 miles of switchbacks that will deposit you at the ruins of an old hotel where you will be rewarded with vistas of the city of Los Angeles with the Pacific Ocean in the distance. Locals call the spot "the Haunted Forest," so get out of there before dark, when stoner teenagers converge on the estate to get paranoid about "flashing lights" (aka flashlights). East Loma Alta Drive at Lake Ave., Altadena.