London Wall

The defence began as a good deal less than a wall. Around AD 100 the ground on the north-western side of Londinium carried only a mound and a ditch, and from around 120 to 150 the Romans put a fort there, held by a large garrison; it is known now as the Cripplegate fort, after the city gate later built on its northern wall. In the late second or early third century that fort was absorbed into a defence running right around the town, its north and west walls thickened and doubled in height to serve as part of the new circuit. Why Londinium warranted so large and costly a fortification is not known.

One suggestion connects it to the invasion of northern Britain by the Picts, who overran Hadrian's Wall in the 180s. Another links it to the political crisis of the late second century, when the governor of Britain, Clodius Albinus, was consolidating his power after claiming the right of succession as emperor; his rival Septimius Severus defeated him in 197 at the Battle of Lugdunum, near Lyon. Whatever prompted it, the money spent on the wall, and Septimius's later campaigns in Scotland, improved Londinium's financial prosperity in the early third century.

Built of Kentish ragstone barged from quarries near Maidstone, the wall ran 2 miles (3.2 km) around about 330 acres (130 ha) and stood up to 20 ft (6 m) high, its length and size making it one of the biggest construction projects in Roman Britain. The gateways were set to meet the network of Roman roads, and the original five, clockwise from the west, were Ludgate, Newgate, Cripplegate, Bishopsgate and Aldgate; Aldersgate was added around 350, and Moorgate came later still, in the medieval period, as no more than a postern. Work continued until at least the end of the fourth century, placing the wall among the last major building projects the Romans undertook before their departure from Britain in 410.

For its first two centuries the town had no wall against the Thames: excavated timber waterfronts pushed some 115 feet (35 m) out into the river between the late first and the mid-third centuries. After Londinium had been raided several times by Saxon pirates in the late third century, work on an additional riverside wall began in 280, carried out in phases, with repairs around 390.

That the riverside section existed at all was long doubted for want of evidence, until excavations at the Tower of London in 1977 showed that the stretch of inner curtain wall between the Lanthorne and Wakefield Towers, south of the White Tower, had originally been the eastern part of the Roman riverside wall, built or rebuilt in the late fourth century. Because it may have limited access to the Thames, commercial and otherwise, it may also reflect a reduced level of activity within the city.

The end of Roman rule around 410 left the wall to fall slowly into disrepair, although Romano-British culture did not vanish with it: settlement in the St Martin-in-the-Fields area of Westminster persisted until about 450. The Anglo-Saxon Chronicle records the Romano-British falling back on London after their bloody defeat at the Battle of Crecganford, at Crayford in Kent, at the hands of the Saxon leaders Hengist and Horsa in 457, which suggests the walls still carried some military value; the Chronicle, though, was written many centuries later, and whether the battle happened at all is uncertain.

From about 500 an Anglo-Saxon settlement called Lundenwic grew up slightly west of the abandoned Roman city, in the vicinity of the Strand. In 886 Alfred the Great, King of Wessex, formally agreed terms with the Danish warlord Guthrum over the territory the Viking incursion had won, the Scandinavians holding the Danelaw across eastern and northern England behind a boundary running roughly from London to Chester. In the same year the Chronicle recorded that London had been refounded by Alfred, and archaeology shows what that meant on the ground, the abandonment of Lundenwic and a revival of life and trade inside the old Roman walls. It was part of Alfred's policy of building an in-depth defence of Wessex against the Vikings, and of mounting an offensive strategy against those who controlled Mercia; the burh of Southwark was created on the south bank in the same period.

How much of the Roman work still stood is another question. Two charters, of 889 and 898, refer to a part of the riverside wall near the dock at Queenhithe, but there is no evidence of any post-Roman restoration of it, so those stretches are unlikely to have counted for much in the city's defences. The city walls were repaired as London grew slowly, until about 950, when urban activity increased dramatically, and a large Viking army that attacked the London burh was defeated in 994.

By the eleventh century London was beyond all comparison the largest town in England. Winchester had been the capital of Anglo-Saxon England, but from this point London was the main forum for foreign traders and the base for defence in time of war; in Frank Stenton's judgement, "It had the resources, and it was rapidly developing the dignity and the political self-consciousness appropriate to a national capital." That size and importance brought a redevelopment of the defences: after the Norman Conquest the walls were given crenellations, further gates, and additional towers and bastions. The ditch outside the wall was restored too, apparently re-cut in 1213 to a V-shaped six feet (1.8 m) deep, a stretch of it remembered in the street name Houndsditch. Moorgate remained a small postern into the marshy ground of Moorfields, north of the wall, until 1415.

The circuit was not fixed for good. Edward I gave the Dominican friars leave to demolish and re-route the length of wall between Ludgate and the Thames, which they did in stages between 1284 and 1320, carrying the walled area west as far as the River Fleet so that it enclosed their precinct, an extension likely to have improved the defensibility of Ludgate. Outside the walls the limit of the city's jurisdiction was marked by city bars, toll gates at Holborn, Temple, West Smithfield and Whitechapel, whose control was vital to the city's privileges over certain trades. When the Great Fire swept the city in September 1666, almost everything medieval inside the wall was destroyed; the wall and its gates came through it.

The seven gates into the City of London, repaired and rebuilt many times over the centuries, all came down between 1760 and 1767 as the expanding city sought to improve the flow of traffic. Work to demolish the walls themselves went on into the nineteenth century, though large sections were absorbed into other buildings rather than cleared away.

The sheer scale of bombing and destruction of buildings during the Blitz revealed numerous parts of the wall. At 00:15 on 28 August 1940, in the pre-wave of bombing before the Blitz proper, buildings and parts of the wall between Fore Street and St Alphage's churchyard gardens near Cripplegate were destroyed, and clearing the rubble exposed walling unseen for over 300 years. On 29 December 1940 heavy bombing produced the conditions that became known as the Second Great Fire of London, and the damage laid bare a section of wall at Noble Street, near the Museum of London.

Peace brought its own losses. In 1957 a 64-metre section was uncovered during works on the London Wall road and then destroyed to accommodate the road changes and to make way for a new car park; eleven metres of it were preserved. In 1984 the Museum of London set out a Wall Walk from the Tower of London to the museum, marked by 23 tiled panels, a number of which have since been destroyed. One of the largest and most easily reached fragments stands just outside Tower Hill tube station, and further remains survive in the basements of the One America Square building and the Old Bailey. Since the Second World War conservation work has preserved the surviving sections as scheduled monuments, and the wall is owned and managed by English Heritage.