The knights of St.John built underground granaries known in Maltese as 'il-fosos', to store wheat as near possible to their centres of activity in the main harbour. The Floriana granaries are the most famous. These were capable of storing 57328 'salma' (equivalent to around 290,000 litres). These were still in use hundreds of years later, especially during world war II when food supplies brought by escorted convoys were at the mercy of the German and Italian warplane and warships.