Presented is a modular building unit that includes a top end with a top surface, a bottom end with a bottom surface; a first plate assembly embedded in the top end, and a second plate assembly embedded in the bottom end. The first plate assembly includes a first plate with a threaded hole, a plurality of anchoring rods coupled to the first plate and embedded in the top end, and a threaded rod mated with the threaded hole. One end of the threaded rod is embedded in the top end and the other end extends out of the top end. The second plate assembly includes a second plate with an unthreaded hole, and a plurality of anchoring rods coupled to the second plate and embedded in the bottom end.