Arroyo Seco features 7 miles of hiking trails near Pasadena, CA.
Take I-210 towards San Fernando (West coming from Monrovia, East coming from Tujunga), and exit Arroyo Parkway/Windsor Ave. Head north, go past the Jack in the Box, cross Woodbury Ave, go 1 mile and look for the parking lot on your left. Street parking is available on side streets from Windsor Ave. This place fillls up early in the morning, particularly in the hot summers.
http://www.tripleblaze.com/trail.php?c=3&i=1668