We often point to Japan as a successful case study in liberal land-use regulation driving housing affordability, but Athens isn't such a bad example either. https://www.bbc.com/culture/article/20191011-the-surprising-story-of-athens-offbeat-architecture

Here's how it worked. (Stop me if I'm going too fast.) Homeowners all over the city were allowed to turn their houses into apartments without much fuss. There were height limits and they couldn't build on archeological sites. That's it.

As a side benefit, this construction boom contributed to three decades of 7% (!) GDP growth, made space for hundreds of thousands of refugees, and (some say) helped to end the Civil War...

...but some[ʷʰᵒˀ] thought that Athens could be prettier and more neoclassical, so who is to say if it was a success, right?

The liberal land-use and tax rules that allowed for this phenomenon have mostly ended, leaving underemployed architects with little to do other than come up with clever ways of missing the point of the antiparochi boom.

So the moment has mostly passed, but we forget the lessons of post-Civil War Athens at our own peril: Let people build housing and they will do it! And it will have a whole boatload of side benefits for society!