How about infra-sound? A 3-10 Hz siren is easy to construct, and the siren's output can be piped to a phased array to generate a beam.
I know that livers and stomachs resonate at about 6Hz, and that resonating such organs would cause people to be violently sick.
A 6Hz beam should be low enough frequency to overcome the impedance mismatch between concrete and air, therefore it should move right through most buildings, even through most bearing walls.
It would be physically large, of course, at least several meters on a side.
If one left the phased array off, and used a horn and dispersive reflector, it might be a dandy way to make people go away, though.