My PC is close to an adjoining wall but not ON ONE. In between my comp station and my neighbors apartment is their wall, my 50 inch flat screen tv that sits on a stand, then after that is a window, and then my PC stand/station. I have neighbors above me, but I live in a majority black/hispanic/asian building. And haven't seen anyone moving giant magnets upstairs lately lol. My upstairs neighbors have a stereo system. But that sits I believe above our second bedroom in the apartment. Which is way at the end of the house. I don't think that could affect anything way in the living room. Also I believe PC's and monitors have a metal casing to protect from any EMI's. That and the ferrites on my vga cable which are also to neutralize EMI's.
They are doing construction of some sort in my neighborhood. But nothing heavy. Just the usual New York stuff where they build those scaffoldings with the blue top? And the metal pillars? And you can walk underneath them like a tunnel? There aren't any jackhammers, magnets, or heavy stuff that I know of. I think they're just gentrifying a few ugly buildings if that.