Montfichet's Tower

Before London spread over it, the Fleet was the biggest river in the area after the Thames, and it formed the western boundary of the Roman city; the strategic importance of its junction with the Thames means the ground was probably fortified from early times. The Normans reinforced the line by building two castles inside the Roman walls that ran north to south, giving their name to the street of Old Bailey before dropping down to the river. Baynard's Castle stood where the wall met the Thames, overlooking the mouth of the Fleet. Montfichet's Tower lay further north on Ludgate Hill, above the strategic route west through Ludgate and over the Fleet that would become Fleet Street.

Little is known of the tower's construction. The first documentary trace is a reference to the lord of Montfichet's Tower in a charter of about 1136 concerning river rights, though the building itself was probably raised in the late 11th century. The name appears to derive from the Montfitchet family of Stansted Mountfitchet in Essex, who occupied the tower in the 12th century; a William Mountfichet lived in the reign of Henry I, from 1100 to 1135, and witnessed a charter for the sheriffs of London. The 16th-century historian John Stow ascribed the building to a Baron of Mountfichet who came to England during the Conquest — Montfiquet is a village in Normandy between Bayeux and Saint-Lô. The same family built Stansted Mountfitchet Castle in Essex, and the two are easily confused, particularly given how variably the name is spelt in the documents.

The last mention of the tower as a place of military significance comes in Jordan Fantosme's chronicle of the revolt of 1173–1174 against Henry II. Fantosme relates how Gilbert de Munfichet strengthened his castle in London and made an ally of "Clarreaus", identified as his cousin Walter Fitz Robert of Baynard's Castle, grandson of the Lord of Clare.

Robert Fitzwalter of Baynard's Castle, who would lead the barons' revolt that culminated in Magna Carta in 1215, plotted against King John in 1212; John got wind of it and exiled him, and Fitzwalter fled to France. On 14 January 1213 the king destroyed Baynard's Castle. Stow reports that Robert Montfichet was banished the same year and that at least one of the Montfichet castles was demolished. Fitzwalter was forgiven under the terms of John's submission to Pope Innocent III in May 1213, had his estates restored on 19 July, and by Stow's account was licensed to repair Baynard's. How far either castle was rebuilt after 1213, or whether the two sites were amalgamated in some way, is not clear; the tower was certainly in ruins by 1278, when a deed between the Bishop of London, the Dean and Chapter of St Paul's and the Dominicans set out where the new friary church should go.

In 1275 Fitzwalter's grandson, another Robert, was licensed to sell Baynard's Castle to Robert Kilwardby, Archbishop of Canterbury, for the precinct of the great Dominican priory at Blackfriars, whose construction began in 1276. Montfichet's Tower was included in the sale. The Bishop of London had first pick of the stones for the 'New Work' rebuilding Old St Paul's between 1256 and 1314, and the remainder went into the new priory church. Building the priory required the Roman walls to be rerouted in 1282, and the military function of the two castles passed to a new tower in the river at the end of the walls, started under Edward I, completed in the reign of Edward II between 1307 and 1327, and demolished in 1502.

The 1278 deed remains the best documentary evidence for where the tower stood, placing it between Ludgate and the river and inside the line of the city walls, with Baynard's Castle to the south. A 1980s study of medieval London's topography narrowed the site to the ground bounded by Ludgate Hill and Carter Lane, and by St Paul's deanery and the city wall. Redevelopment let the Museum of London's Department of Urban Archaeology excavate the area between 1986 and 1990. Two east–west ditches on the north side of Carter Lane were read as the tower's southern defences, the later of them V-shaped and originally some 16 metres wide and 5 metres deep; another ditch lay about 30 metres north on Ludgate Hill. Pits and a well between them were interpreted as the bailey, but no sign of a keep or other masonry was found; Watson suggests a motte and keep may have lain east of the Ludgate Hill entrance of Ludgate Square.