Residents of the upscale Porter Ranch district of Los Angeles enjoy open spaces and neighborhood trails overlooking the vast San Fernando Valley. These are publicly accessible trails, so you don't have to be a resident to wander through the remaining vestiges of two riparian canyons and a cliff-rimmed hillside blanketed with aromatic sage. Suitable for horses and mountain bikes as well as hikers, these trails are best taken on a cool, clear January or February day, preferably when the often-murky L.A. air is replaced by the clean, dry air of a Santa Ana wind or by the infusion of fresh, cold air from the north following the passage of a storm front.

For a complete tour of the trails, follow the directions below, covering an eight-mile route. You can abbreviate the route as desired, of course.

Park on Rinaldi Street, west of Tampa Avenue, and pick up the equestrian trail going north through a landscaped linear park along Limekiln Canyon's trickling creek. After crossing the creek twice on bridges you come to a split (0.7 mile) where one branch of the trail bends easily left and follows a ravine toward a newer subdivision. Take the main branch (right), which goes up toward the shoulder of Tampa Avenue. You pass under a concrete bridge (a gated entrance road serving houses west of Limekiln Canyon), pass a junction with the Palisades Trail (your return route), cross Sesnon Boulevard, and finally join the Sesnon Trail, 1.8 miles from the start. Follow the Sesnon Trail east over a hump to Ormskirk Avenue. Turn south, walk through Porter Ridge Park, and go left on Sesnon Boulevard to where it dead ends on the edge of steep-sided Aliso Canyon. Walk around the pipe gate on the left and down into Aliso Canyon.

After following Aliso Canyon for 1.3 miles, turn right on the Palisades Trail. You double back up a ravine, climb a slope, pass some houses, and reach Reseda Boulevard. Cross Reseda, continue uphill on the west sidewalk for about 0.3 mile, and then veer off on the wide trail, bordered by a wooden fence, descending left along a sage-covered slope.

Soon you start contouring along the base of some craggy, sedimentary bluffs -- the so-called palisades. You're well above the valley floor here, so the view takes in thousands of rooftops in the foreground and the purple Santa Monica Mountains rising above the valley haze in the south.

At 6.5 miles the Palisades Trail goes over a saddle, and then it drops down to Tampa Avenue. Pick up the Limekiln Canyon Trail on the far side and return to your car, retracing your earlier steps.