Paris, Lyon and Marseille use a grotesquely intricate election system btw.
*is curious*
Seems to have been amended by now, if
this site is to be trusted.
Used to be that, in normal towns, two thirds of seats were proportional and the remainder went top-up to the winner (and winner meant second-round winner, with lists over 10% advancing to runoffs unless someone took 50% on the first round...) - ensuring a solid majority for whoever won but a few seats to the opposition to make its voice heard.
In Paris, Lyon and Marseille that system was used for the arrondissements, or the
secteurs (of two arrondissements each, with the old arrondissements now only statistical entities) in marseille. And at the same time, each Arrondissement sent a (roughly proportional to population) no. of deputies to the city council - taken proportionally from the Arrondissement council.