The current architecture is largely due to Haussmann's reforms and reconstruction of the city in the 19th century under Napoléon III. That was when what was left of medieval Paris was swept away and replaced by the wide boulevards and the architecture you see there today. You can still see a fair bit of older stuff if you look around for it though.

If you're asking specifically about the roofs though, the design is older than that, dating back to the 16th century. It wasn't until Haussmann that they completely took over Paris.