When we first moved into our apartment block, our neighbours reported that they'd had bicycles stolen from inside the building (usually from the garage) and they weren't really sure how folks were doing it. At least one time it had been because the old garage door had been wrenched open, but this more recent time it seemed to be more of a mystery - no sign of damage or forced entry. They discussed wanting to install a camera to record what was going on with the garage, so we offered to sort something out for them (given that we're the gadget nerds of the building and had an idea of how to do it on the cheap).

Main problem: we had to figure out how to get wifi down to the garage. First we tried extending our wifi network down there, but that proved super flakey (concrete is not a great connectivity vehicle). Eventually, we worked out that the garage was able to pick up our network over powerline, so we set up an airport down there to connect to that and feed a connection to a mounted Dropcam (they annoying only work on wifi).

We've had the camera in there for about a year now, and we've caught a few incidents - neighbours breaking the garage door, that sort of simple thing, but then finally we caught the "stealing a bike from a locked garage" trick:

So, in short. Make sure your garage door always closes behind you.