The gatehouse was built in the early C15th15th century,{{sfn|Salzmann|1901|p=243}} during the time when John Leem was prior.{{sfn|Salzmann|1901|p=221}} A basement at moat level served either as a cellar or prison.{{sfn|Salzmann|1901|p=243}} The building is about {{convert|50|ft|m}} high and contains four storiesstoreys, including the cellar.{{sfn|Cooper|1853|pp=153-54}}
In the C16th16th century, a stone bridge was built over the moat. The gatehouse and bridge are [[Grade I listed buildings]].<ref name=Gatehouse>{{cite web |url=http://www.heritagegateway.org.uk/Gateway/Results_Single.aspx?uid=1191633&resourceID=5 |title=BARBICAN TOWER AND BRIDGE OVER THE MOAT AT MICHELHAM PRIORY |publisher=Heritagegateway |accessdate=13 June 2016}}</ref>
