Most palaces doubled as places of business, on the ground floor, and homes above. The ground floors, which even when built were probably rather prone to periodic flooding, have relatively few rooms, and a rather grand stairway leading to the residential upper floors, where ceilings are rather low by the standards of palaces. The portico on a canal allowed goods to be loaded and unloaded, and led to a large space called the "androne", where they were stored and business transacted. Upstairs, the "portego" or "salone" was another large room, centrally placed and usually "T"-shaped, received light from the windows and was the main space for dining and entertaining. To the rear an open staircase led to a small courtyard with a well-head and often a rear door to the street. In fact there are no true wells in Venice, and the well-head led down to a cistern sealed from the salty groundwater, which collected rainwater from the roof and courtyard through stone gutters leading to a sand filter system and the cistern.