I know i'm comparing apples to oranges here, but seeing as some of the problems are of the same kind (gentrification, middle class getting pushed out), and both

I know i'm comparing apples to oranges here, but seeing as some of the problems are of the same kind (gentrification, middle class getting pushed out), and both the cities as they are today were mostly built in the 19th century... Paris is 40 sq.mi. and has a density of 55,000/sq. mi (even more if you count out the 2 vast wooden uninhabited areas that take up 10% of the city's surface). Meanwhile it's extremely friendly to pedestrians and still preserves quite a good standard of living for the inhabitants. And the city is mostly a big museum, meaning there are monuments all around town and most of the buildings in numerous parts of the city are protected and thus cannot be redeveloped. Oh and in most of the city you can't build above 25 meters. In this regard it would seem from a purely outer point of view that there must still be a lot of room for new construction in San Francisco.