My interest in iron grids ( officially access cover/manhole covers but I can draw myself to use those names) has only recently evolved compared to that of doors, although similar notion drew me to them.
Quietly sitting there, being run over or trodden on all day, they barely get noticed. Some are quite plain and aren't worth a second glance, others are complex geometeric patterns.
My favourites are the Jas Bartle covers that can be found around London. I tried to find some more details on Jas Bartle and all I could find was a reference to a J.M.Bartle Iron Founders, "It may be noted that the iron founders who supplied the materials were J. M. Bartle and Company, a local firm with premises in Lancaster Road". If anybody knows anything more about these guys I'd like to know if you have the time to tell.