[vladvasiliu]

Single-family homes are built out in the suburbs. In the city proper, they build multi-story buildings. There are SFH inside the city limits, but these are old, and I'm not aware of any such new developments.

But the thing is, just like elsewhere, much fewer people actually want to live out in the suburbs, which is reflected in the price. Because getting to Paris proper sucks if you don't have a direct rail connection (which most of the outer 'burbs don't), and even then, you're likely to waste hours commuting, between the unreliable service and just sheer distance. Things are improving for "mid-distance" suburbs, but we're not quite there yet.