London has no single builder. Its creation spans two millennia of invasion, commerce, fire, plague, empire, and renewal—each era inscribing itself on the urban fabric. The question "Who built London?" reveals not a name but a collective biography of a city that has continually remade itself.
The Romans established Londinium circa 43 CE at the lowest bridging point of the Thames. They built the first London Bridge, a defensive wall (sections visible today), forum, amphitheater, temples, and port infrastructure. Londinium became Britannia's provincial capital—population ~60,000. Roman street grid influences modern City of London layout.
Post-Roman abandonment gave way to Saxon Lundenwic (Covent Garden area). Alfred the Great refortified the Roman walls (886). Norman conquest brought the Tower of London (1078), Westminster Hall (1097), and the first stone London Bridge (1176). Medieval guilds, churches (St. Paul's), and markets shaped the commercial city.
Tudor/Stuart expansion beyond walls. Great Fire (1666) destroyed 80% — Christopher Wren rebuilt 51 churches + St. Paul's. West End development (Covent Garden, Mayfair). Docks expanded east. Population exploded: 200K (1600) → 1M (1800).
Industrial revolution: railways, sewers (Bazalgette), Underground (1863), embankments. Suburban expansion via rail. Population 6.5M (1900) — world's largest city. Imperial capital architecture: Houses of Parliament, Albert Hall, V&A.
Blitz destruction (WWII) → post-war reconstruction, Brutalist estates, Docklands regeneration (1980s–), Canary Wharf, The Shard (2012), Crossrail/Elizabeth Line (2022). Immigrant communities from former colonies and Europe continuously reshape neighborhoods, cuisine, culture.
Romans, Saxons, Normans, merchants, guilds, monarchs, engineers, immigrants, developers, planners, communities. London builds itself daily—through planning decisions, preservation battles, grassroots activism, and the accumulated actions of 9 million residents. It is a verb, not a noun: London is forever being built.