Beneath the basement of a nondescript office block at 85 Gracechurch Street, archaeologists from the Museum of London Archaeology made a discovery in February 2025 that rewrote a chapter of the city’s founding narrative. Buried under concrete and filing cabinets, they found the foundations of Londinium’s first basilica – a 2,000-year-old administrative heart built from Kentish limestone, roughly 40 metres long and 20 metres wide, with walls standing over a metre high. “This is so significant – this is the heart of Roman London,” Sophie Jackson, MOLA’s Director of Development, told the BBC. “This building will tell us so much about the origins of London, why London grew and why it was chosen as the capital of Britain.”
The irony is exquisite. As we continue to excavate the physical foundations of London’s Roman identity, the linguistic foundation – its very name – remains one of the most stubborn unsolved puzzles in British toponymy. It is a question that has occupied antiquarians, linguists, and curious Londoners for centuries. After two millennia of scholarship, no one can say with certainty what “London” actually means.
The Oldest Clue: A Letter from the First Century
The earliest written mention of London does not come from a grand historical chronicle. It comes from a fragment of a Roman letter, discovered in London in 2016 and dated to between AD 65 and 80. Written in Roman cursive on a thin sheet of wood, it reads simply: Londinio Mogontio – “In London, to Mogontius.” Mogontio, it transpires, shares its root with Mogontiacum, the Celtic name for the German city of Mainz.
The discovery pushed back the earliest physical evidence of London’s name by nearly two decades. Before this find, the first recorded reference was the historian Tacitus’s account of Boudica’s revolt in AD 60–61, in which he described Londinium as “much frequented by a number of merchants and trading vessels.” That Tacitus called it Londinium rather than something else tells us the name was already established by the early second century – but it tells us nothing about where the name came from.
Plowonida: The River That Named the City
The most intellectually ambitious attempt to solve the puzzle belongs to Richard Coates, Emeritus Professor of Linguistics at the University of Sussex, whose landmark 1998 paper “A New Explanation of the Name of London” remains the most cited modern etymology. Coates proposed that the name ultimately derives from a pre-Celtic hydronym – a river name from the Old European stratum of toponymy identified by the German linguist Hans Krahe.
His reconstruction traces the chain: a Proto-Indo-European root **pleu-*, meaning “to flow” or “to swim,” combined with **nejd-*, meaning “to flow,” produced a compound river name **Plowonida* – a “wide, flowing river.” This name, Coates argued, would have been applied to the Thames precisely where it widens into its tidal estuary near the present City. The Celtic settlement on its banks then took its name from the river: **Plowonidonjon*, which through Celtic sound changes became **Lowonidonjon, and eventually, under Roman Latinisation, Londinium*.
The theory is elegant but not without critics. Lacey Wallace, a place-name scholar, has described the derivation as “somewhat tenuous.” The compound form is unusually rare for river names in the Indo-European family. And there is a further wrinkle: if the name derived from **Londinjon*, the Old English form should have been **Lyndon through i-mutation, not Lunden. Coates himself acknowledged the difficulty and suggested the local British Latin pronunciation may have shifted to Lundeiniu*, bypassing the expected sound change.
King Lud and the Goddess Luna: The Mythic Etymologies
Before Coates’s scholarly intervention, the most popular explanation was also the most romantic. Geoffrey of Monmouth’s Historia Regum Britanniae, written around 1136, claimed the city was named after a mythical king called Lud, son of Heli, who supposedly rebuilt and ruled the settlement. The legend was propagated for centuries – even the London Stone, that enigmatic relic once embedded in Cannon Street, was sometimes called “Lud’s Stone.” Modern scholars have thoroughly debunked the Lud theory: there is no evidence such a figure existed, and the etymology does not withstand linguistic scrutiny.
A related but distinct theory links the name to the Celtic word lond, meaning “wild” or “fierce,” suggesting the settlement was named for its untamed surroundings. The Italian linguist Giovanni Alessio proposed in 1951 a Ligurian origin from **lond-*, meaning “mud” or “marsh,” though this too has been largely discounted – there is no evidence of Ligurian settlement in Britain. More recently, in 2013, the Dutch linguist Peter Schrijver revived a variation, deriving the name from a proto-Indo-European root **lendh- (“to sink, to flood”), arguing that Londinion* meant “the place that floods” – a fitting description for a riverside settlement on the tidal Thames.
The Boudican Scar: When London Burned
Understanding the name requires understanding the place – and London’s earliest identity was forged in catastrophe. In AD 60 or 61, Queen Boudica of the Iceni led a revolt against Roman rule that destroyed three cities: Camulodunum (Colchester), Verulamium (St Albans), and Londinium. The Roman governor Suetonius Paulinus, unable to defend the settlement, abandoned it to the rebels. What followed was devastating. Roman historians Tacitus and Cassius Dio recorded the slaughter; modern archaeology has confirmed it in a distinctive stratum of red-ochre ash and charcoal, scattered with shattered pottery and twisted ironwork, that runs beneath the streets of the Square Mile. Archaeologists call it the “Boudican Destruction Horizon” – London’s first geological timestamp, a fingerprint of apocalypse baked into the soil.
The city rebuilt. A military fort was established around AD 63 to garrison between 500 and 800 soldiers, and within a decade Londinium had largely recovered. By the second century, it had grown to perhaps 30,000 or 60,000 people, replacing Colchester as the provincial capital. Its forum basilica – the predecessor to the structure MOLA uncovered in 2025 – was one of the largest buildings north of the Alps when Emperor Hadrian visited in AD 122. The name Londinium had survived the flames.
From Londinium to London: A Thousand Years of Sound
The modern name “London” did not spring fully formed from Londinium. The journey took nearly a thousand years and passed through at least half a dozen linguistic layers. When the Romans withdrew in the early fifth century, the city was abandoned and its population dwindled. The Anglo-Saxons, who colonised the surrounding area, created their own names: Lundenwic (roughly “London trading town,” from the Latin vicus), Lundenburh (“London fortress”), Lundenbyrig, and Lundenne. The 9th-century History of the Britons recorded the Old Welsh name as Cair Lundem or Lundein.
After the Norman Conquest of 1066, the name gradually standardised. French, Latin, and Dutch influences from the new ruling class, combined with the fixing effects of the printing press and early maps, stripped away the variant spellings. By the late medieval period, “London” had won – though alternative forms like Lundin, Londoun, and Londen persisted in some texts well into the early modern period.
The City That Keeps Naming Itself
What the etymology reveals, ultimately, is not a single origin but a palimpsest – a document written over repeatedly, each layer partially visible beneath the next. The pre-Celtic hydronym **Plowonida, if Coates is right, tells of a river. The Roman Londinium tells of an administration. The Anglo-Saxon Lundenwic* tells of commerce. Each name captures a moment in the city’s reinvention of itself – a process that continues to shape the streets we walk today.
And the reinventions continue. In 2025, the discovery at 85 Gracechurch Street means that the public will eventually be able to walk through glass floors and look down upon the very walls where Roman magistrates once delivered judgements – a new layer of meaning added to a site that has been continuously significant for nearly two thousand years. As Chris Hayward of the City of London Corporation put it: “The fact that Roman London is beneath your feet is, frankly, quite a remarkable emotion to experience.”
Perhaps the mystery of the name is not a problem to be solved but a condition to be embraced. London has always been a city whose identity is layered, contested, and incomplete – a city that survives by absorbing its own destruction and rebuilding on top of it. The name London may mean “the wide, flowing river.” It may mean “the place that floods.” It may carry some meaning lost to the centuries between the Bronze Age and the Roman conquest. What it certainly means, after two thousand years, is this: the city endures.
Sources and Further Reading
Coates, R. (1998). “A New Explanation of the Name of London.” Transactions of the Philological Society, 96(2), 203–229. Wiley Online Library
Jackson, K.H. (1938). “Nennius and the 28 Cities of Britain.” Antiquity, 12(45), 44–55.
Schrijver, P. (2013). “The Rise of London from the Iron Age to the Roman Period.” In The Impact of Rome on Cultures in NW Europe, ed. J. Brandt et al.
Museum of London Archaeology (MOLA). “Uncovering the Heart of Roman London.” mola.org.uk
BBC News. “Beginnings of Roman London Discovered in Office Basement.” 12 February 2025. bbc.com
