Complete the text with articles where necessary ( romans invaded britain in ad 43 and,chasing ancient britons along ( thames ,they came to ( place where it was easy to cross.they built ( garrison there -and london was born.they also erected ( bridge over ( river.( garrison became ( major trading post.later,( suffered neglect and ( whole area was raided by ( vikings .in ad 886alfred ( great drove out ( raiders, ( bribge was repaired and ( city prospered again.( hundred years later,( vikings returned but king ethelred sailed up (, attached ropes to london bridge, headed downriver and pulled it down.