<P> The abutments of modern London Bridge rest several metres above natural embankments of gravel, sand and clay . From the late Neolithic era the southern embankment formed a natural causeway above the surrounding swamp and marsh of the river's estuary; the northern ascended to higher ground at the present site of Cornhill . Between the embankments, the River Thames could have been crossed by ford when the tide was low, or ferry when it was high . Both embankments, particularly the northern, would have offered stable backheads for boat traffic up and downstream--the Thames and its estuary were a major inland and Continental trade route from at least the 9th century BC . There is archaeological evidence for scattered Neolithic, Bronze Age and Iron Age settlement nearby, but until a bridge was built there, London did not exist . Two ancient fords were in use a few miles upstream, beyond the river's upper tidal reach . It seems that the course of Watling Street was aligned with them and led into the heartlands of the Catuvellauni, who at the time of Caesar's invasion of 54 BC were Britain's most powerful tribe . Some time before Claudius's conquest of AD 43, power shifted to the Trinovantes, who held the region northeast of the Thames Estuary from a capital at Camulodunum, nowadays Colchester in Essex . Claudius imposed a major colonia on Camulodunum, and made it the capital city of the new Roman province of Britannia . The first London Bridge was built by the Romans as part of their road - building programme, to help consolidate their conquest . </P> <P> The first bridge was probably a Roman military pontoon type, giving a rapid overland shortcut to Camulodunum from the southern and Kentish ports, along the Roman roads of Stane Street and Watling Street (now the A2). Around 55 AD, the temporary bridge over the Thames was replaced by a permanent timber piled bridge, maintained and guarded by a small garrison . On the relatively high, dry ground at the northern end of the bridge, a small, opportunistic trading and shipping settlement took root, and grew into the town of Londinium . A smaller settlement developed at the southern end of the bridge, in the area now known as Southwark . The bridge was probably destroyed along with the town in the Boudican revolt (60 AD), but both were rebuilt and Londinium became the administrative and mercantile capital of Roman Britain . The upstream fords and ferries remained in use but the bridge offered uninterrupted, mass movement of foot, horse, and wheeled traffic across the Thames, linking four major arterial road systems north of the Thames with four to the south . Just downstream of the bridge were substantial quays and depots, convenient to seagoing trade between Britain and the rest of the Roman Empire . </P> <P> With the end of Roman rule in Britain in the early 5th century, Londinium was gradually abandoned and the bridge fell into disrepair . In the Saxon period, the river became a boundary between the emergent, mutually hostile kingdoms of Mercia and Wessex . By the late 9th century, Danish invasions prompted at least a partial reoccupation of the site by the Saxons . The bridge may have been rebuilt by Alfred the Great soon after the Battle of Edington as part of Alfred's redevelopment of the area in his system of burhs, or it may have been rebuilt around 990 under the Saxon king Æthelred the Unready to hasten his troop movements against Sweyn Forkbeard, father of Cnut the Great . A skaldic tradition describes the bridge's destruction in 1014 by Æthelred's ally Olaf, to divide the Danish forces who held both the walled City of London and Southwark . The earliest contemporary written reference to a Saxon bridge is c. 1016 when chroniclers mention how Cnut's ships bypassed the crossing, during his war to regain the throne from Edmund Ironside (see Battle of Brentford (1016)). </P> <P> Following the Norman conquest in 1066, King William I rebuilt the bridge . The London tornado of 1091 destroyed it, also damaging St Mary - le - Bow . It was repaired or replaced by King William II, destroyed by fire in 1136, and rebuilt in the reign of Stephen . Henry II created a monastic guild, the "Brethren of the Bridge", to oversee all work on London Bridge . In 1163 Peter of Colechurch, chaplain and Warden of the bridge and its Brethren, supervised the bridge's last rebuilding in timber . </P>

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