If you love human diversity, Barcelona ain’t a bad place to be, particularly as much of that diversity can be spanned in an evening’s walk, slipping through neighbourhoods of various affluence, textures, smells, noise and colour. But this is enabled by apartment-living and jeek-by-jowl population density. Here, a house with a garden arouses curiousity. And you occasionally see where a long-term resident has acheived an abundance of mature greenery in a balcony-sized biosphere. Otherwise, the trees that line the neighbourhood streets and arterial avenues are a mere distraction; an ambience creator shot through by the metal menace, noise and fumes of a vast colony of motorists that thread in, out and around this city incessantly, daily. Which is why, when I walk up into the very hills we could blame for Barcelona’s urban intensity, I so clearly recognise Robert MacFarlane’s sentiment, “the relief of relief” (in The Wild Places).