I needed an easy hike to counter the stressful week I had at work. This trail is easy to find and easy to hike. I followed a route which was once a road, most of which was washed away decades ago. I barely felt tired after this 8 1/2 mile round trip over mostly flat terrain. Starting in Altadena, Arroyo Seco Trail is the first 4 miles of the 28.5 mile Gabrielino Trail.