London Wall, Roman defensive wall in City of London, United Kingdom.

London Wall surrounded the historic City of London as a Roman fortification with sections up to six meters tall and three meters wide. The structure ran from what is now Tower Hill to the western edge of the settlement, enclosing roughly 330 acres (130 hectares).

Work on the defensive structure began around 200 CE, enclosing the Roman settlement of Londinium with five main gates leading to major Roman roads. After the Romans withdrew, the Saxons extended the fortification, and medieval builders renewed it several times.

The fortification's gates shaped the medieval city's layout, and their names still appear on street signs across the financial district today. Visitors can trace how these passageways channeled trade and urban life over centuries.

Preserved sections appear at Tower Hill, Noble Street, and the Barbican area, with the Museum of London providing dedicated viewpoints. Most spots sit outdoors and can be reached on foot, while some covered areas remain accessible during rain.

The wall's gateways aligned with the Roman road network, and the modern streets entering the former walled area still follow the same routes through the former medieval gates. Aldersgate was added around 350, and Moorgate began as a secondary postern in the medieval period.