North Berkeley is characterized by scattered rock outcroppings, seen today in the numerous neighborhood parks and paths as well as in front and back yards. In the early twentieth century, this area was largely undeveloped. That changed dramatically as the first decade progressed, especially after the San Francisco earthquake.
Fortunately the developers of the period worked with the landscape instead of against it, building around rocks (and trees) instead of blasting them out of the way. Dating from this period as sort of a signature by the developers, the stone entry pillars that appear at some intersections around the area are made from the local rock and support the natural but urban character.
You are quite visible here from all directions, so stealth is key. The cache is not on the pillar, not in the street, and not on private property – stay on the sidewalk. Make sure the cache is closed securely before replacing.
Reference: Berkeley Rocks, Building with Nature, by Jonathan Chester (Ten Speed Press).