Naz good idea. The only place they could go is on the roof terrace. This is large space on the corner of the building, open on three sides with the other side being a 12' north facing wall. There are no eaves at all to put the nests under so do you think a position, high on this wall, would be too open for the HMs? To explain further, this is modern block of flats and I own the flat directly below the roof terrace. So this means I would have to run wires from the nest box on the roof terrace, down the wall, then down the front of the building into my flat. I don't think other residents would be too happy about that, in fact I probably wouldn't be allowed to do it. Hence a wireless option would have been perfect but not if I've got to disturb the birds putting a new battery in everyday. Plus the expense of it of course. I think at the very least, even if the camera option is out, I will put up a few nesting boxes if you think the site is suitable. Sorry this is so long but difficult trying to explain.