First pic - Excelsior 'hood, showing McLaren Park's blue water tower, from a walkway near the Glen Park BART.
Lyell is the main under-freeway sidewalk access for walkers between the neighborhoods. There you can turn to the east to trek up the Portola (second pic: lower Portola on Gladstone just above Cambridge; Bernal Heights in distance) or west for the Excelsior. The Excelsior begins at Mission Street, at the top of which 'hood is McLaren Park, over 300 acres.
The enclosed pedestrian overpass that will take you from south Bernal Heights to the lower Portola is further to the east. Before that is a stairway leading up to Mission from Alemany (third pic).
Continuing steeply uphill from Mission on Avalon to Athens: London, Paris, Lisbon, Madrid, Edinburgh, Naples, Vienna, Athens (fourth pic: view from Lisbon & France: Mount Davidson in distance).
Today's hike was a combination of leisurely, exploratory wandering and checking out the ongoing remake of the slope on the north side of the Athens stairway (99 steps) in the upper Excelsior 'hood called the Athens/Avalon GreenSpace Project:
There are only a few plants showing up now but the curved concrete retaining walls look great and there's a concrete wall at the bottom with a low sit-on top. The next two pics are THENs that show this hillside as it looked several years ago before work was started.
When you get to the top of the stairway you're at Valmar Terrace & Athens. There's a short enclosed sidewalk from the top of the steps out to the street. The next street steeply downhill from here is Peru. The Peru/Valmar stairway starts to your right (south). It climbs from Athens & Peru to Valmar Terrace (last two pics, 77 or so steps).
Heading back downhill, at Cayuga & Lamartine is a benched minipark down to Alemany with a ramp, no steps.
Finally, from Tingley to San Jose between Theresa and Cotter where a long, steep ramp (can be seen on Google Maps) over the John F. Foran Freeway took me to Circular and Monterey in the Sunnyside 'hood where I was a couple blocks west of the Glen Park BART and my beginning.