Polygon 'footprints'

[JoeBorgione]

I have a polygon feature set that represents urban renewal projects (see sample image of data below). The original polygons were derived by dissolving parcels; hence the regular linear gaps which are where street centerlines are.  I'd like to do something akin to aggregate polygons however, given that quite a number of the projects abut others, aggregate is out. Basically, what I'd like is something that looks like the red outline footprint I've sketched around a couple of the project areas; is there a tool to do such a task rather than drawing by hand?

[DanPatterson_Retired]

Points... if it were a polygon, then you wouldn't need a concave hull