Yes - but how many houses could you tear down and build something like that with CURRENT building codes? IIUC, you need 6 ft of space on each side of the lot f

Yes - but how many houses could you tear down and build something like that with CURRENT building codes? IIUC, you need 6 ft of space on each side of the lot for fire code. That takes away the majority of available floor space. You could build something 4-storeys, but after stairs, you'd be left with half as much leasable floor space...