The old centre was formed by rings of canals with unique mostly 17th century residences of wealthy merchants, financiers, craftsmen, doctors, lawyers, politicians and artists. Because of lack of space, these houses were mostly narrow, not more than 30ft wide (9 meters). They are are characterized by big narrow windows, decorative gable tops, very narrow stairs inside and pulley outside to transport larger objects to upper floors. Very often the residences served also as businesses. Merchant’s houses had their storage in attics and cellars. Sometimes the lift was installed in the middle of the house plan, to transport the goods between floors. The office of the merchant was usually on the ground floor. Like in Venice the canals were the main way of transporting the goods.