Barcelona is one of the densest cities in Europe. And Márton Mogyorósy's recent photo series, called Barcelona from above , does an excellent job of demonstrating that. My favorite photo is this one here, showing La Barceloneta neighborhood adjacent to the beach:
https://www.instagram.com/p/Bsa78llAC2c/
None of the buildings are particularly tall (maybe 6 or 7 storeys at the most), but the streets are probably only about 6m wide, including sidewalks. This is one way that you can achieve density without height and it is a good example of what I was getting at in my post, European-style height, but not density .