The history of London begins with the landing of the Romans on the British Isles in 43 AD. In order to cross the River Thames, the troops led by Aulus Plautius built a bridge across the river. The Roman settlement on the northern bank of the Thames, called Londinium, becomes a trade center. Around 200 years the city was surrounded by a fortress wall, which for almost a millennium, determined its size. After the fall of the Roman Empire, London fell into disrepair - the population shrank sharply, the buildings collapsed. Only at the beginning of VII century, the city began to revive. Around 604, the first St Paul's Cathedral was built. In the 9th century, London, once again a thriving trading center, became a prey to the Vikings. Until the 11th century, the city was owned by the Normans, the Vikings, and the English. In the middle of the 11th century, King Edward the Confessor asserts Anglo-Saxon rule over London. London's medieval history dates back to 1066 when William the Conqueror