I studied architecture & environmental planning at university (until I dropped out) so perhaps the obsession stems from there. I find it amazing how places I know well have changed over the years.
I've also hoarded books about Newtownards, Belfast, Antrim & the Ards Penninsula. They are currently in residence at my parents' house, but I managed to pick up two I haven't seen before today in Belfast. The Masonic Lodge at CornMarket were having an exhibition of these old photos, so we went in for a nosy. Two books for £5.