The Mansarts were by all means a family of architects: Jules had 2 grandsons who became architects and his great-uncle, François Mansart, even though he did not invent it (he just helped popularizing it) took credit and gave his name to the "Mansard roof" (with an adulteration of his name) which you see quite often at the top of the buildings. Both buildings at the front of the picture below (taken from the top of the Arch of Triumph) have Mansard roofs.

Jules-Hardouin Mansart  was the second architect of Versailles, he designed the Place Vendôme in Paris:

and the Royal chapel of the Invalides: