I came across this French paper over the weekend, while I was at the gym pretending to work out my legs. It is a fascinating look at the evolution of Parisian urbanism from 1600-1902, including how the city's height limits have changed over the centuries. Here, for example, are two section diagrams showing the allowable building envelopes for both an 8 meter street and a 10 meter street:

The way to read these is to start at the bottom with the width of the right-of-way ("voie"). As you move up, it then gives you the allowable heights for various dates. So for example, in 1667, the allowable building height for a 10 meter street was 15.60m. After this height, there was then a requirement to stepback following a 45 degree angular plane. Or in some cases, following a certain radius:

We don't have a ton of 8 and 10-meter wide streets here in Toronto, but there are obvious similarities between what is shown here and what is in our mid-rise design guidelines. Of course, the big difference is that we're mostly zoned for low-rises houses and Paris is not. This broader context matters a great deal and it's why I keep asking: Are you sure you want Parisian-style urbanism?