MT Terrace Medium Pair Brick 3b
It's almost impossible to take a rail journey through any of the (once) industrial areas of England, Wales and Northern Ireland without seeing the backs of streets of terraced housing (though they're very much rarer in Scotland, where tenement blocks were the norm).
Here's a typical pair, which can be made up into rows as required (the thumbnail shows half of a front and the back). This version is in an authentic sooty South London brick texture derived from a photo kindly supplied by PaulSW2.
The FBX/PBR main mesh is quite high in polys, however there are four levels of LOD making the use of even large groups very feasible, as they'll also share the same 2048sq texture maps.