"Visiting Maryhill": we leave Elin on Great Western Road. On the ground, in front of an abandoned shopfront, small squares of glass form a rectangular carpet, or circles covering part of the pavement - a lighting system for the basement stores below, Mark explains. I met him that same morning, and he generously offered to walk me through what turns out to be his childhood neighbourhood, beginning by revealing, hidden behind trees, a place I would not otherwise have found.