Followed trail that begins on the east side of lower Rubio Canyon that pretty much follows the mountain's ridge line with a very significant incline to the top of Muir Peak that took about 3~4 hours. Spectacular views of San Gabriel Valley, Eaton & Rubio Canyons, Echo Mountain & Mt Wilson. Returned via Inspiration Point, Castle Canyon trail to Echo Mountain & Sam Merrill Trail, but used the cut-off at power lines to return back to lower Rubio Canyon. Very strenuous hike.