Office building constructed from very few faces and array modifier. Although low poly (kind of ..), I think it's good enough to use as background in closer shots. For faraway shots, you can delete the 'Floor' object inside the building to save a few polygons.

2 Textures needed, one for glossy and transparent windows, another one for the wall color which can be changed in the nodes. There's minor distortion on the glass to mimic unevenness in real building. Environment textures is not included, you can use any texture out there.