Tristan Hotham

Researcher of campaigns and platforms. Maker of other things.

The largest city on Earth: six thousand years of the world’s biggest cities

Title card reading 'The largest city on Earth' in black, red and gold on pale paper, beside a world map with dots for every city that has been the world's largest and a line coloured from purple to yellow tracing the centre of the 25 largest cities from Mesopotamia across Central Asia, up over the Arctic and down to Tibet, and below it a line chart of the largest city's population rising from Uruk to Dhaka.

Six thousand years ago the largest city on Earth had perhaps 80,000 people. Today it has 41.9 million. I followed the crown from Uruk to Dhaka, through Babylon, Rome, Chang’an, Baghdad, Beijing and London, and watched the centre of the urban world wander across the map.

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Read the paper

Which was the biggest city in the world in 1000 BC? Or AD 1000, or 1800? Nobody counted, so the answers rest on the patient work of historians who pieced together city sizes from walls, tax rolls, travellers and early censuses. Two of them, Tertius Chandler and George Modelski, produced the best known compilations, and in 2016 Meredith Reba, Femke Reitsma and Karen Seto turned both into an open, geocoded dataset. After cleaning it holds 1,654 places and 10,033 population estimates from 3700 BC to 1975. For 1975 onwards I used the United Nations’ new World Urbanization Prospects 2025, which projects every city to 2050.

Put them together at 85 snapshot dates and 30 different cities have been the largest on Earth on their own.

World map. Dots mark every city that has been the world's largest, grouped in labels: Sumer (Eridu, Uruk, Lagash, Mari, Girsu, Ur), Mesopotamia and Persia (Babylon, Nineveh, Ctesiphon, Baghdad, Merv), Egypt (Memphis, Avaris, Thebes, Pi-Ramesses, Alexandria), Rome and Constantinople, China (Yin, Linzi, Chang'an, Kaifeng, Hangzhou, Nanjing, Beijing), London, New York, Tokyo, Dhaka and Jakarta. A line coloured from purple to yellow by date traces the centre of the 25 largest cities: it loops around Mesopotamia and Central Asia for millennia, swings north over the Atlantic and the Arctic in the nineteenth and twentieth centuries, and ends over Tibet and Nepal
Every city that has been the world’s largest, and the path of the centre of the 25 largest cities from 3700 BC to 2050.

From Uruk to Rome

Uruk, in the marshes of southern Iraq, was the largest city in every snapshot from 3500 to 2800 BC, reaching about 80,000 people. Its record stood for 700 years, until Ur reached 100,000 in 2100 BC. Then the crown moved between the capitals of Egypt and Mesopotamia, Memphis, Babylon, Thebes and Pi-Ramesses, with one interruption: Yin, the capital of China’s Shang kings, in 1300 BC. In the first millennium BC the big cities multiplied in China and India too, and Linzi, Alexandria and then Rome took the lead. Modelski puts Rome at 1,200,000 in AD 200; Chandler, more cautious, never gives ancient Rome more than 450,000.

Line chart on a log scale of the population of the largest city from 3700 BC to 2050, rising from about 6,000 to 80,000 at Uruk, around 100,000 to 200,000 for Babylon, close to a million for Alexandria, Rome, Chang'an and Baghdad, dipping to about 200,000 to 700,000 between 1100 and 1750, then climbing steeply through Beijing, London, New York and Tokyo to over 40 million in Jakarta and 52 million projected for Dhaka in 2050. A coloured band underneath shows the region of the largest city, mostly red for West Asia early on, teal for East Asia from 1100 to 1825, blue for Europe in the nineteenth century, then teal and pink for East and South-East Asia
How big the biggest city was. The band shows where it was; dashed lines show each compilation’s own leader.

Seven centuries of Chinese capitals

After Rome came Constantinople, Ctesiphon, Chang’an (today’s Xi’an) and Baghdad. From 1100 the crown settled in China: Kaifeng, Hangzhou, Nanjing and then Beijing were the largest city in the world in 13 of the 16 snapshots between 1100 and 1825, broken only by Merv in Central Asia and Ottoman Istanbul. Strikingly, the largest city stayed below a million all that time: between 1100 and 1750 it never held more than 900,000 people in these estimates.

The largest city of 2025 is 38.1 times the size of the largest city of 1800.

London’s century

London was 13th in Chandler’s list in 1600. By 1800 it was second only to Beijing, and in 1825 it was 1.1% behind, closer than either figure can be trusted. By 1850 it was clearly the largest city in the world, with 2,320,000 people, and it stayed on top in every snapshot to 1914. In 1925 Chandler has New York and London level, 0.4% apart. Drawing straight lines between the snapshots, London’s reign ran from about 1826 to 1925: roughly 99 years.

Line chart on a log scale from 1500 to 2050 of London, Beijing, Istanbul, Paris, New York and Tokyo. London, in thick red, climbs from under 100,000 in 1500 past Beijing in the 1820s and leads until New York's steep line catches it in the 1920s; a shaded band marks London as the largest from about 1826 to 1925. After 1975 the UN lines show Tokyo far above the rest
London and its rivals. The shaded band is London’s reign as the world’s largest city.

The wandering centre

To see the big picture I found the population-weighted centre of the 25 largest cities at every snapshot. Until 800 BC it never left Mesopotamia and its neighbours. As China and India filled up with cities it moved east to Central Asia, and it stayed there, between 59°E and 82°E, from AD 500 to 1825. Then the industrial cities of Europe and America yanked it 5,102 km west in a single century: in 1900, 13 of the 25 largest cities were European. Since 1975 it has raced back east and south. In 2025 it sits over eastern Tibet, and by 2050 it is projected over eastern Nepal, with 19 of today’s 25 largest cities in Asia and 1 in Europe.

Stacked area chart of the share of the 25 largest cities' population by region from 3700 BC to 2050. West Asia in red dominates the earliest millennia, with North Africa in gold; East Asia in teal takes over from the first millennium AD; Europe in blue swells in the nineteenth century to more than half by 1900, joined by North America in navy; after 1975 East, South and South-East Asia hold most of the share
Where the 25 largest cities were, by region.

What counts as a city?

The UN’s 2025 revision defines a city by the Degree of Urbanisation: a continuous cluster of 1 km grid squares with at least 1,500 people per square kilometre and at least 50,000 people in all, drawn from satellite-based population grids, ignoring official boundaries. That reshuffles the familiar rankings. Jakarta, not Tokyo, is the largest city in the world in 2025, with 41.9 million, and Dhaka is second with 36.6 million. American cities shrink, because their suburbs are not dense enough. You can see the effect at the 1975 seam: Chandler’s New York had 17,100,000 people, the UN’s 12,076,416. I have not blended the two kinds of figure: before 1975 is Chandler and Modelski, after is the UN.

Paired bar chart of Chandler's 12 largest places in 1975 against the UN's figure for the same city that year. Tokyo is similar in both at about 23 to 24 million; New York falls from 17.1 million to 12.1 million; Moscow, London, Paris and Rio de Janeiro are also smaller in the UN's count, while São Paulo and Buenos Aires are slightly larger
The same cities in 1975, counted two ways.

2050

In the UN’s projections Dhaka passes Jakarta in 2049 to become the largest city in the world, with 52.1 million against Jakarta’s 51.8 million, a margin of 0.7%, small enough to call a tie. Karachi gains 11.2 million and enters the top ten. Luanda grows by 78%, Dar es Salaam by 69%, and Lagos climbs from 26th to 21st. Tokyo, the largest city in the world for a generation, is projected to shrink to 30.7 million.

Dumbbell chart of the 15 largest cities of 2050, with an open circle for 2025 and a solid circle for 2050: Dhaka grows from 36.6 to 52.1 million, Jakarta from 41.9 to 51.8 million, then Shanghai, New Delhi, Karachi (from 21.4 to 32.6 million), Cairo, Tokyo (shrinking to 30.7 million), Guangzhou, Manila, Kolkata, Mumbai, Seoul (shrinking), Bangkok, Lahore and Luanda (from 11.4 to 20.3 million)
The largest cities of 2050 in the UN’s projection, and how far they have to grow.

How sure can we be?

Not very, before the modern era. Where both compilations have figures for at least 8 places, they name a different largest city at 10 of 15 snapshots. In AD 1000 Modelski gives Baghdad 1,500,000 people; Chandler gives it 125,000 and crowns Cordoba in Spain instead. The record is also thin outside Europe, the Middle East, India and China: before AD 1000 the compilations hold 11 places in the Americas and 4 in sub-Saharan Africa. And the data needed fixing: Modelski’s cities in the Americas carried exact copies of their AD figures 1,300 years too early, and a few figures were out by a factor of ten, such as Philadelphia at 17.6 million in 1914. Everything I changed is listed in the paper.

Line chart on a log scale of the number of places of 100,000 or more and of a million or more at each snapshot. Places of 100,000 rise from a handful before 1000 BC to around 20 for most of the next two thousand years, then climb from the 1600s to several hundred by 1900; places of a million appear in 1800 with one, reach 16 in 1900, and the UN counts 511 in 2025 and 6,172 places of 100,000
How many cities passed 100,000 and a million. Before 1975 these count only places in the compilations, so they are floors.

How I did this

I used the V2 files of Reba, Reitsma and Seto’s dataset, read as Windows-1252 text, and the UN World Urbanization Prospects 2025 files 18 to 21. At each snapshot every place gets its compiler’s figure for that date, or a log-scale interpolation between the compiler’s nearest dates if they are close enough in time; where both compilations give a figure I take the average, and places within 0.5% of the top count as tied. From 1975 the figures are the UN’s alone. The paper sets out every step, every correction and every caveat, and the code and data are open.

Explore the interactive version
Read the paper
Data and code

Notes and sources

  • Reba, M., Reitsma, F. and Seto, K. C. (2016) Spatializing 6,000 years of global urbanization from 3700 BC to AD 2000, Scientific Data 3, 160034; data on figshare, CC BY 4.0. From Chandler, T. (1987) Four Thousand Years of Urban Growth and Modelski, G. (2003) World Cities: -3000 to 2000.
  • United Nations, Department of Economic and Social Affairs, Population Division (2025) World Urbanization Prospects: The 2025 Revision, CC BY 3.0 IGO.
  • Natural Earth country outlines (public domain).
  • I wrote the text, with drafting and editing assistance from Claude (Anthropic), which also helped prepare the analysis code. I reviewed and checked all text and results.

Tristan Hotham

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