Trailhead is at mile 7 on Mountain Loop Highway in Granite Falls (set odometer to 0 at left turn onto Mt Loop Highway)
Green Mt Road is across the street. Look for brick monument on south side of highway.
Starting at the original Robe townsite (1893-1917), the trail goes along the Everett & Monte Cristo Railroad grade and past (through?) rail tunnels.
http://www.robecanyon.org/Images/robe_canyon_map_line_drawing.jpg
Photos http://www.robecanyon.org/Photos.html
http://www.iphlogger.com/hikes/old-robe-trail.php
http://wasteam.railfan.net/emcr/2004_07_26_Robe/2004_07_26_Robe.html
About the trail:
http://www.iphlogger.com/hikes/old-robe-trail.php
http://washingtonhikes.com/2005/oldrobe/index.html
http://www.washingtonhikes.com/2003/oldrobe/index2.html