History: London, England, United Kingdom

th century King Edward the Confessor re-founded and rebuilt Westminster Abbey and Westminster, a short distance upstream from London became a favoured royal residence. From this point onward Westminster steadily supplanted the City of London itself as a venue for the business of national government.
Following his victory in the Battle of Hastings, William the Bastard, Duke of Normandy, was crowned King of England in the newly finished Westminster Abbey on Christmas Day 1066. William constructed the Tower of London, the first of the many Norman castles in England to be rebuilt in stone, in the southeastern corner of the city to intimidate the native inhabitants. In 1097, William II began the building of Westminster Hall, close by the abbey of the same name. The hall became the basis of a new Palace of Westminster.
During the 12th century the institutions of central government, which had hitherto accompanied the royal court as it moved around the country, grew in size and sophistication and became increasingly fixed in one place. In most cases this was Westminster, although the royal treasury, having been moved from Winchester, came to rest in the Tower. While the City of Westminster developed into a true capital in governmental terms, its distinct neighbour, the City of London, remained England's largest city and principal commercial centre and flourished under its own unique administration, the Corporation of London. In 1100 its population was around 18,000; by 1300 it had grown to nearly 100,000.
Disaster struck during the Black Death in the mid-14th century, when London lost nearly a third of its population. Apart from the invasion during the Peasants' Revolt in 1381, London remained relatively untouched by the various civil wars during the Middle Ages.