A portcullis is a latticed wooden or metal gate which could be raised on ropes or chains using a winch. They often have spikes on the bottom, and were used mainly in castles as a form of defence. There were usually two portcullises at the entrance of the building. The first would be raised, then closed before the inner gate was raised. This trapped enemies in the short corridor between the two gates, where they could be picked off by arrows or killed with burning material dropped from above.