London has no specific foundation date either. Shortly after the Roman conquest of 43 AD the invaders grasped the strategic significance of the river Thames, slicing through the flattest, most fertile portion of their new province, its estuary providing easy access to the European mainland.

With the collapse of Roman administration Londinium was abandoned in the fifth century. As farming people the invading Anglo-Saxons, who gradually pushed the native Romano-British westwards, had no taste for city life and preferred to found villages which are now London's suburbs or satellites such as Fulham, Mitcham, Ealing and Barking.

The Norman invasion of 1066 was marked by the construction of the mighty Tower of London, located both to protect London Bridge from raiders coming upstream and sited athwart the city's eastern wall, to overawe its inhabitants as a symbol and embodiment of royal power.

London as much as anywhere else in Europe was devastated by the epidemic of bubonic plague, known as the Black Death, which carried off a third of the population in 1348-9.

The population of London tripled under the Tudors, making it not only the nation's greatest city but by far the greatest - almost a hundred times more populous than the Stratford on Avon in which Shakespeare grew up before coming to bustling Bankside as actor-manager at the Globe Theatre.

By 1700 London's population had passed the half million mark, ranking it with Paris and Naples as one of Europe's three largest cities.

Victorian London found its perfect chronicler in Charles Dickens, whose home in Doughty Street survives as his museum.

When Edward VII ascended the throne in 1901 London was the largest city in the world, with a population of over six millions. A century later it is still the largest city in Europe.