Paris also has famously tiny, cramped and frankly unlivable appartments. Has had for ages. The three musketeers even contained references to it...

If Paris is a model for the world, I don't want this world.

By curiosity I checked some numbers to compare. Paris density is just crazy! When compared, Berlin (mentioned by cameldrv) really has a low density for the huge capital it is, at around ~3.9k persons/km². London seems to have around 5.5k, New York around 10.2k, while Paris is at a crazy 20.7k!

Numbers from https://versus.com/en/berlin-vs-london-vs-new-york-vs-paris/....

It's a bit exaggerated because Paris proper is only a small part of the urban region. It's more appropriate to compare Paris to Manhattan. Both house around 2 million people at 20k people/km², and both are in sprawling metropolitan areas of 10-20 million depending where you stop counting.

Yes, but Paris proper is notable for achieving that density with only two tall buildings, both non-residential.

Edit: And a considerable amount of land given over to parks, museums, churches, and other non-residential spaces.

As dmurray commented there's differences in what is counted. Another difference is that Paris proper has relatively small parks, whereas Berlin has several huge ones as well as lakes.

So yeah, Paris is dense, but if you compare block by block the differences are smaller.

Even the (by far) most dense borough of Berlin is only at 14,373/km²[1], though. That's considerably lower than almost all of the Parisian boroughs[2]. Even the whole city's average is 20,000/km². From the point of view of most American cities with some obvious exceptions, the difference is probably indeed not that noticeable though.

[1] https://de.wikipedia.org/wiki/Verwaltungsgliederung_Berlins

[2] https://en.wikipedia.org/wiki/Arrondissements_of_Paris