Bois de Boulogne,
This famous park-forrest in the western suburbs of Paris contains no less than 7 lakes with a total arrea of about 20 ha. They can all be fished - and small carp are present in them all. Bigger fish to 15 kg+ are caught quite frequently, and a few topping the 20-25 kg mark has graced the nets of lucky anglers as well. The biggest from Lac Inferieur, which is the biggest of the lakes. Silver grasscarp has been stocked to feed on the abundant green algae - and some of them go to more than 15 kgs. The fishing is said to be quite temperature sensitive in these shallow lakes, and location is therefore very important, as the banks are traveling quite a lot, according to conditions.
Even though the lakes are situated in a city park, there should be reasonably peacefull most days, so you can enjoy the fishing. The Timbre étang APNLE is needed, and 3 rods are authorized. Nightfishing is not allowed. 

Canal Saint-Martin, Paris.
Carp of 14,5 kg reported.

Port-aux-Cerises, Draveil,
Carp of 14 kg caught during an enduro.

Seine.
Over the years, incredibly many big carp has been caught off  „Les Quais" in central Paris. The pillars of the many bridges are known hot-spots. 15 kg+ carp are no rarity here, and 20 kg+ fish has been caught with the Eifel Tower in the background! The many common carp here averaging about the 8 kg makes the basis of the fishing here, with the much heavier mirrors as the icing on the cake.
Besides opposite the Eifel Tower, known hot-spots are Barrage de Suresnes, Pont de Lavallois, Barrage d’Alfortville and Pont d’Ivry.