History: London, England, United Kingdom

The Welsh word for London is Llundain from Middle Welsh Llundein and the Welsh u descends from either proto-Celtic oi or ou. As with the Romano-British theonym Nodons from Noudont- ", Celtic ou was sometimes transcribed as Latin o. According to established Celtic sound change laws, if Llundain were descended from a former Londiniom, we would expect to see Llondyn or Llyndyn in Welsh, but a hypothetical Lou-nd-e-njo-m would yield Welsh Llundain according to the same sound change principles. The element lou- is a widely attested Proto-Indo-European root meaning ‘wash’.
Prehistory and antiquity
Although there is evidence of scattered Brythonic settlements in the area, the first major settlement was founded by the Romans in 43 AD. This lasted for just seventeen years and around 61, the Iceni tribe led by Queen Boudica stormed it, burning it to the ground. The next, heavily planned incarnation of the city prospered and superseded Colchester as the capital of the Roman province of Britannia in 100. At its height during the 2nd century, Roman London had a population of around 60,000. By the 7th century, the Anglo-Saxons had created a new settlement called Lundenwic over a mile (2 km) upstream from the old Roman city, around what is now Covent Garden.