TG doesn't surface 90 degree planes, so you have to cheat it a little, by putting in a slight slant. Saying that, Kadri's cube object population would probably give you the best results, as hard displacements tend to crack at corners.
Here's something I was playing with using modulo set at 100m in x,y,z, which warped a PF to create a 100m chequred patern that used the grey value to displace verticly. The edges are smoothed using the same modulo output to drive a half cycle sine curve which is compressed into a square shape with a gain shader and clamped with a colour adjust, this is used to multiply the chequred output to give the sides a gradient to avoid the 90 texture stretch.
The windows use the same function to create the towers, but this time set to a modulo distance of 10m.