the building's basement is about 60% subterranean and 40% above ground. this was common among houses, castles and palaces at the time. on top of the basement sits the piano nobile, the most important and impressive floor of the building, primarily used for receiving guests. notable to the design are the four round towers at each of the four corners of the building. these form four independent stairwells and lead from the basement up to the piano nobile and the second floor.