Trailin' in from Presidio Blvd. at Lovers Lane (first pic) and south of the Mountain Lake Trail, soon down 30 steps for the old stairway to El Polin Spring (next three pix). Amazing how this area has transformed from bare and newly planted to gorgeously green in such a short time. Birds and butterflies but no other humans down here when I was. Up 69 steepish wood steps on El Polin's west side (fifth pic) for this newer Presidio stairway to the Ecology Trail.
Took a lower trail I assumed would merge with the main Ecology Trail, but it ended at a large, cleared-out, flattish area covered with netting and wood chips. At regular intervals were pipes enclosed in a kind of cage. No idea what this is supposed to become. Walked along the edge of this with the Ecology Trail just above. Picked a spot and slogged through thick ivy a short distance to the main trail, reminded of my offtrail wanderings before Mount Sutro's trail improvements began.
The Ecology Trail curves around a short distance behind Main Post buildings. Followed it out to its east trailhead at Hardie, just across from the Inn at the Presidio's back patio. Down 36 steps to the next street level (pics 6, 7, 8), then onto a minor trail not hiked in a while. This, just below the street, led me to the Lovers Lane footbridge where a walking group was gathering (last pic).
Curved round to the #43 bus stop on Presidio Blvd. to take me out of the park.