On route 90 going into Boston, there are two examples of where the space above the highway system has been built over. One is a a hotel, the other, a supermarket. For how much of our cities are taken up with the road systems of on ramps, and off ramps and overpasses, why isn't this done more? Space is at such a premium and you see huge freestanding storage buildings and parking garages along the highway on prime real estate, yet there is so much space above and below the roads that isn't touched. Shouldn't architecture follow function, and its location reflect that function as well as practicality? I think there are much more creative ways to see the unused space of our cities, especially since with ever-growing populations, these previously ignored spaces are becoming more valuable. Wouldn't it make so much more sense, on a planning and organizational level, to place parking and storage and warehouses, possibly even shopping malls and grocery stores, at these large intersections of road where we have unused space? Easy access and high visibility, cheaper land, and central locals would make this a no-brainer I'd think.