Around 47–50 AD, Roman engineers chose a low gravel rise on the north bank of the River Thames — the first point upstream where the tidal river could be bridged and still reached by seagoing ships — and founded Londinium. Nearly two thousand years later that single bridgehead has grown into Greater London, one of the largest urban areas in Europe. This relief map lets you scrub through that growth on a stylised 3D terrain of the Thames valley.
The Square Mile — today's financial "City of London" — still roughly follows the footprint of the Roman and medieval walled city, even though modern Greater London around it is over 600 times larger.
An interactive 3D relief map of the Thames valley that grows from the Roman bridgehead of Londinium in 50 AD into modern Greater London, revealing the river, the old city wall and famous landmarks as you scrub through history.
How London's location — a bridgeable, tidal point on the Thames — determined its founding site, and how the built-up area expanded outward in distinct historical waves rather than gradually.
Drag the Year slider from 50 AD to today to watch the city footprint and landmarks appear in order. Toggle the Roman wall, landmarks and river flow, and exaggerate the relief to see the Thames valley more clearly.
The modern "Square Mile" financial district still traces the boundary of the Roman and medieval walled city, even though Greater London today covers over 600 times that area.