How to kill time Cheaply in Paris with two children?

[Doryhunky]

We will be in Paris Saturday afternoon between checking out of our hotel and catching the Eurostar.
The kids have already seen the Eiffel
Tower, arc de triomphe, Left Bank, Montmartre and Jardins du Luxembourg. They hate galleries, and relaxing in cafes would be wasted on them. What can I do with them which is low or no cost?

I can’t think of anything free but the aquarium at Val d’Europe is really good and there’s loads of shops there for a wander round if they’re the type to be happy window shopping?

We spent about 2 hours going up and down the external escalators on the Pompidou Centre when the dc were about 3 and 6.

Boat trip ?

Boat trip obvs not free, but likely to entertain all ages.

Crepes and churros...

How old? Are they too big for playgrounds?

Walk and play in Jardins du Luxembourg? Visit the zoo in le jardin desplantes? Both central.

The catacombes? But the queues can be long, not sure if you can prebook?

Pere Lachaise cemetery is great, a maze to wander in and do many stories (Eloise and Abelard etc).
Also La Defence is nice to wander around, weird modern architecture.
Museum to the Deportation I think is free but a bit grim depending on age.
There's a weekly bird market on the Ile Saint Louis.
Waffles in Parc Monceau.

Or there’s a walk based on the highline in New York. The Promenade Plantee.

www.theguardian.com/travel/2017/jun/07/paris-promenade-plantee-free-elevated-park-walkway-bastille-bois-de-vincennes

Looks like it predates the Highline.

When I had time to kill in Paris I went to see the smaller version of the Statue of Liberty - Bir Hakeim metro station is the closest. It's a fair walk though, probably not for tinies.

www.atlasobscura.com/places/statue-of-liberty-pont-de-grenelle

How old are they?

Wow. Thanks for the answers. One is young enough for playgrounds and the other can sit
And watch. The catacombs terrified me when I visited years ago! Pere Lachaise is a good idea. Unfortunately one is a culture vulture and the other is just very active!! If I can bear to spend money the aquarium might work too. Tbh Paris is wasted on the younger one and I find that very frustrating!

Pooh. Just seen more replies. 7 and 12 and very very good walkers!

Pooh is meant to be oooh!

Mine is seven and will spend a bazillion years floating a boat on the pond in the Jardin du Luxembourg, which is cheapish — €3 or 4 per half hour? He also gets a kick out of grave finding in either Père Lachaise or the Montparnasse cemetery — I have a writer or two I often leave flowers for but lose their graves each time, and he likes wayfinding. Glances Bertillon? And getting falafel in the Marais.

La Villette has a lot of free child-directed things at weekends.

Ooooh yes to falafel in the Marais!

A cracking walk is from the Arc de Triomphe to the Petit Palais- free to get into with some Monet's etc. Maybe a tad too cultural for young ones but there's plenty of shops on the Champs Elysees!

Sorry, autocorrect wrecked Glaces Berthillon.

Thanks for all the helpful suggestions. We ended up at Parc de la villette as the weather was good. Lots of amenities here and they are now running around the playground.