Procedural buildings with procedural skybridges and procedural windows and procedural roadmaps
I’ve made a shader for the windows that has interior projection – it appears as though there are rooms inside the windows, but they are actually a cube texture applied to some trig functions. My shader also uses the building’s position as a unique identifier, so each building has a unique color (even though they all use the same material!) Basically, the buildings have a decent amount of detail for very low overhead. I can fit about a thousand buildings in a scene before I dip below 60 frames per second.