Europe is composed of 50 countries and over 800 cities according to the UN. From London to Lisbon, they all have different histories and, most importantly, sizes.

Which cities are the biggest? Some data might surprise, but one thing is certain: London is the biggest city in Europe. Or is it?

Some cities have smaller boundaries than others, so the criteria for their subdivision are varied accordingly. For instance, Paris is the third most populous urban area in Europe; however, since its administrative borders are restricted, the French capital falls in a lower position than it should.

So just how many different answers are the to the question of the largest cities in Europe?

Within the city walls

To start with, there’s an obvious option to define cities in Europe: how the cities define themselves. In terms of the administrative limits of each city, a hierarchy becomes clear.

To avoid getting bogged down in the details of each individual census, national statistics office, or city population office, here’s the listing of European cities by population within city limits.

1. London, UK: 9,002,500
2. Berlin, Germany: 3,664,000
3. Madrid, Spain: 3,305,400
4. Kyiv, Ukraine: 2,920,873
5. Rome, Italy: 2,844,750
6. Bucharest, Romania: 2,161,347
7. Paris, France: 2,139,907
8. Vienna, Austria: 1,930,000
9. Warsaw, Poland: 1,860,000
10. Hamburg, Germany: 1,850,000

[Read more: Where are the largest cities in Britain?]

On the other hand, if you broaden the net and start talking about ‘urban agglomerations’ – basically, cities and the bits around them that also function as part of the city – we get a very different picture.

Near the city walls

There are all sorts of caveats and rules that go into these measurements, from the United Nations Department of Economic and Social Affairs, which published its population estimates in its World Urbanisation Prospects.

The core idea is that by discounting rivers, parks, roads, and industrial fields, urban agglomerations are built-up areas where houses are not more than 200m apart. But the definition doesn’t stretch as far as satellite cities: so London’s commuter belt, with its stretches of the evil greenbelt as a dividing line doesn’t count, but the Parisian suburbs, very much close to and part of Paris proper, do.

And the results of this measure are, obviously, rather different:

1. Paris, France: 10,843,285
2. London, UK: 10,313,307
3. Madrid, Spain: 6,229,254
4. Berlin, Germany: 6,000,000
5. Barcelona, Spain: 5,258,319
6. Rome, Italy: 3,717,956
7. Milan, Italy: 3,098,974
8. Athens, Greece: 3,051,899
9. Lisbon, Portugal: 2,884,297
10. Manchester, UK: 2,645,598

There’s a variant version of this definition, too: one that includes areas that are generally built up but aren’t specifically centred on one particular city. Demographia’s 2023 figures are produced on that basis, and that comes up with a similar picture, but with a very different front-runner:

1. Moscow, Russia: 17,878,000
2. Istanbul, Turkey: 14,441,000
3. Paris, France: 11,108,000
4. London, UK: 10,803,000

Emotionally attached to the city walls

But to everyone who grew up sort of near a big place but not really in the big place, and got sick of explaining to visiting Americans exactly what and where Hemel Hempstead was, there’s another handy definition that produces a picture of the metropolitan area, or functional urban region.

These figures from Eurostat, the statistics arm of the EU, offer that view:

1. London area, UK: 14,031,830
2. Paris area, France: 12,005,077
3. Madrid area, Spain: 6,378,297
4. Barcelona area, Spain: 5,445,616
5. Ruhr area, Germany: 5,045,784
6. Berlin, Germany: 5,005,216
7. Milan area, Italy: 4,267,946
8. Athens, Greece: 3,863,763
9. Rome area, Italy: 3,700,000
10. Warsaw area, Poland: 3,304,641

So, that’s sorted, right? It’s London, or Paris, or possibly the Ruhr.

Except, no. Because Europe itself isn’t that simple, as we’re about to find out.

Whose Europe is it anyway?

There’s the EU, the Schengen Area, the Customs Union, the EEA, the Continent, and then the sticky issue of Europe itself.

So, this list included European Turkey, gives Istanbul the benefit of the doubt, and stretches Europe as far as the Ural mountains in Russia. And then, the size rankings change again:

By city limits (the first definition), here’s how things look:

1. Istanbul, Instanbul, Turkey: 15,840,900
2. Moscow, Russia: 12,632,400
3. London, UK: 9,002,500
4. Saint Petersburg, Russia: 5,376,700
5. Berlin, Germany: 3,664,000

But as before, that definition of the city isn’t particularly useful – as it shunts the continental giant of Paris to the relegation zone purely because the administrative area of the arrondissements is tiny.

With so many fluctuating figures based on so many different definitions, it’s probably more useful to conclude by dividing European cities into three broad classes. Let’s call them megacities, very big cities, and quite big cities.

In the megacity category, we get roughly:

1. Moscow, Russia: 17.9 million
2. Istanbul, Turkey: 14.8 million
3. London, UK: 14 million
4. Paris, France: 12 million
5. Ruhr Area, Germany: 11.1 million
6. Madrid, Spain: 6.4 million
7. Barcelona, Spain: 5.5 million
8. Berlin, Germany: 5.0 million
9. St Petersburg, Russia: 4.8 million
10. Milan, Italy: 4.2 million

And then the rest. Rome, Athens, Warsaw, Lisbon, Manchester, Bucharest, Vienna, and so on, happily muddling along somewhere between two million and four million people.

The more you know.

Bonus point

If your city obsession is beyond entry-level, a brief lesson in megalopolises (megalopoles?). Popularised in the early 20th century, the term applies to a chain of cities that are sort of near each other and can be thought of as working in a roughly coherent whole – the typical example being the north-eastern seaboard of the US, with its smudge of Boston, New York, Philadelphia, Baltimore, and Washington, D.C.

In Europe, for some reason, this has become a battle of the bananas.

According to data from 2017, The ‘Green Banana’ comes in third place, with roughly 40 million people spread between the cities of Gdansk, Warsaw, and Katowice in Poland; Ostrava, Prague, Olomouc, and Brno in the Czech Republic; Vienna in Austria; Bratislava and Zilina in Slovakia; Budapest and Gyor in Hungary; Ljubljana in Slovenia; Zagreb in Croatia; and Trieste in Italy.

In second place we have the Golden Banana, with 45 million or so. The colour comes, in theory, from the luscious sands of the Western Mediterranean, with the megalopolis defined as including Turin and Genoa in Italy; Lyon, Nice, Toulon, Marseille, Nîmes, Montpellier, Narbonne, Perpignan, and Toulouse in France; Monaco in Monaco (obviously); Andorra la Vella in Andorra; and Manresa, Girona, Vic, Barcelona, Tarragona, Catellón de la Plana, Sagunt, Valencia, Alicante, Murcia, and Cartagena in Spain.

But supreme among European transnational megalopolises comes the mighty Blue Banana. This mythological elision of cities harbours 130m people and includes (deep breath in) Liverpool, Manchester, Leeds, Sheffield, Birmingham, and London in the UK; Brussels and Antwerp in Belgium; Amsterdam, Rotterdam, The Hague and Utrecht in the Netherlands; Luxembourg in Luxembourg; Cologne, Düsseldorf, Dortmund, Essen, Duisburg, Wuppertal, Frankfurt, Munich, Stuttgart, and Nuremberg in Germany; Strasbourg and Lille in France; Zürich and Basel in Switzerland; and Turin, Milan, and Genoa in Italy.

[Read more: What is the capital city of each European country and their populations?]

[Read more: Where are the largest cities in the US?]

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