The following text is from the original listed building designation:
WEST MALLING
TQ6857 SWAN STREET 1156-0/3/157 St Mary's Abbey: Tower to original 25/08/59 Abbey (Formerly Listed as: SWAN STREET St Mary'Abbey)
GV I
Ruins of tower of Abbey church. c1090 built by Archbishop Gundulf of Rochester who removed an order of Benedictine monks installed since AD944 and installed Benedictine nuns with an abbess Aricia brought over from Normandy and rededicated the Abbey from St Andrew to the Virgin Mary. The base of the tower is of the early Norman period with late Norman arcading above C14 octagonal corner turrets and with lean-to erected on the east side during the C18 by Honeywood. Built of stone rubble with 2 lowest tiers of arcading of tufa and some Caen stone dressings. West front has projecting corners, the 1st stage having c1090 round-headed arches, the 2nd stage having similar round-headed arches with impost blocks, the 3rd stage with late Norman blank arcading, the 4th stage with late Noman blank arcading which continues across the front and the 5th stage with C14 tall octagonal turrets. Arched doorway with wooden door surround and 6-plank door with iron handle. Above is a paired trefoliated window with quatrefoil above. Tall round-headed blocked arch on either side of doorcase. North front has blocked-in arch to 1st stage and above window with double cinquefoil-headed arch. East front has C18 lean-to built on with 2 double cinquefoil-headed lights resited from other parts of the Abbey and 2-storey central door, the upper probably a hayloft. South front obscured by C20 building built over west side of cloister.
Listing NGR: TQ6829257677

English Heritage, List of Buildings of Special Architectural or Historic Interest (Map). SKE16160.