The Oldest Part of London: The City (Square Mile)

London's ancient core isn't Westminster or the West End—it's the City of London, a 1.12-square-mile (2.9 km²) enclave known as the Square Mile. It's a city within a city, with its own police force, government, and 2,000-year history.

Roman Foundations (43 CE)

The Romans founded Londinium on the north bank of the Thames, bridging the river at the first fordable point upstream from the estuary. The City's boundaries still roughly follow the Roman wall.

Key Landmarks Within the Square Mile

• Tower of London (1078+) — Norman fortress, royal palace, prison, jewel house
• St Paul's Cathedral (Wren, 1675-1710) — replaces medieval cathedral burned in Great Fire
• Bank of England (1694) — "Old Lady of Threadneedle Street"
• Guildhall (1411+) — City's administrative center
• Mansion House (1752) — Lord Mayor's official residence
• Leadenhall Market (14th century origins) — covered market, now dining destination
• Roman sites: London Wall fragments, Amphitheatre (Guildhall Yard), Mithraeum (Bloomberg HQ)

Unique Governance

• Lord Mayor (annual, distinct from Mayor of London)
• Court of Common Council — 100+ elected common councilmen
• Liveried Companies — 110+ ancient trade guilds (Mercers, Grocers, Fishmongers...) with voting rights
• City of London Police — separate from Met Police

Continuity & Change

The City burned (1666), was bombed (1940-41), and rebuilt repeatedly. Yet its street pattern, ward system, and institutional memory persist. Modern skyscrapers (Gherkin, Cheesegrater, Walkie-Talkie) now punctuate the medieval plan.

Not to Be Confused With

• City of Westminster — political capital (Parliament, Buckingham Palace)
• Greater London — 32 boroughs + City, 600+ sq mi, 9M people

The Square Mile is where London began—and where its financial heart still beats.