barbican

A barbican (from medieval Latin barbecana, "outer fortification of a city or castle," a general Romanic word, perhaps from Arabic or Persian cf. bab-khanah "gate-house" and "towered gateway" or from the mediaeval English burgh-kenning ) is a fortified outpost or gateway, such as an outer defense to a city or castle, or any tower situated over a gate or bridge which was used for defensive purposes. Usually barbicans were situated outside the main line of defences and connected to the city walls with a walled road called the neck.