The Roman soldiers on Hadrian's Wall lived in forts, milecastles and turrets along its length. There were 16 forts along the Wall, and 5 supply forts just to the south. Each one could house a whole cohort of soldiers (480 men). Every Roman mile (about 1.5km), there was a milecastle. These could house up to 64 soldiers, but usually had less. There were 2 turrets between each pair of milecastles. These were garrisoned by 4 soldiers. They were like 2-storeyed castle towers. Downstairs was for cooking and storage. Upstairs was for sleeping. The roof was the lookout station. Beacons could be lit to warn of attacks from the Picts. The signal could then be sent along the Wall from turret to turret.