London: The Geography and History Behind Britain's Capital

London grew from a Roman river port of a few thousand people into a metropolis of roughly nine million. A guide to the geography and history behind the city.

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Why the Romans chose the Thames

London exists because of a river crossing. In around AD 47 to 50, Roman engineers established Londinium at the lowest point where the Thames could reliably be bridged, close enough to the sea for shipping yet far enough upstream to avoid the worst of tidal flooding. The settlement grew quickly into the largest city in Roman Britain, though it was burned to the ground in AD 60 or 61 during Boudica's revolt before being rebuilt as the provincial capital. Sections of the Roman city wall, built around AD 200, still stand near the Museum of London and the Tower of London, marking the boundary of what residents still call the 'Square Mile', the City of London's modern financial district.

From medieval capital to imperial metropolis

London's population reached roughly one million by 1800, making it the largest city in the world at the time, and it kept growing through the Industrial Revolution as the hub of an empire that at its peak governed a quarter of the globe's population. That growth left an architectural record spanning centuries within a short walk: the Tower of London, begun by William the Conqueror in 1066, sits a few miles from Christopher Wren's St Paul's Cathedral, rebuilt after the Great Fire of 1666, which itself sits within view of glass-and-steel towers built in the last twenty years. Westminster Abbey has hosted every English and British coronation since 1066, with the sole exceptions of Edward V and Edward VIII.

A city of villages

Modern Greater London, home to roughly nine million people, is often described as a collection of villages that were gradually absorbed into a single urban area rather than a city planned from a single centre, and the patchwork of distinct neighbourhoods, from Georgian Bloomsbury to Victorian Notting Hill, still reflects that piecemeal growth. The London Underground, opened in 1863 as the world's first underground railway, was central to stitching these areas together, and today moves around five million passengers on an average weekday across 11 lines and 272 stations.

Museums, parks and getting around

London's major national museums, including the British Museum, the Natural History Museum and the Tate galleries, are free to enter, a policy dating back to the nineteenth century that makes the city's cultural depth accessible regardless of budget. Eight Royal Parks, including Hyde Park and Regent's Park, provide close to 5,000 acres of green space across the centre. Most visitors budget three to five days to see a reasonable cross-section of the city, and May through September offers the most reliable weather, though London's museums and many attractions operate comfortably year-round.

Frequently Asked Questions

Why was London founded where it was?

The Romans chose the site around AD 47 to 50 because it was the lowest point on the Thames that could be bridged reliably, close to the sea but above the worst tidal effects.

Are London's national museums free?

Yes, permanent collections at major national museums including the British Museum, Natural History Museum and Tate galleries are free to enter, though special exhibitions usually charge admission.

How big is London's population?

Greater London has a population of roughly nine million, making it by far the largest city in the United Kingdom and one of the largest in Europe.

How many days do you need to see London?

Three to five days gives a reasonable overview of the major sights, though the city's size means most visitors leave with places still unseen.