;)
We went back to here the next day and purchased one of the puzzles.
A translation of the festival website is here.
Arc de Triomphe | The Sunday Bird Market | Context Tour "The Belly of Paris" | The Eiffel Tower | Houseboats on the Seine | Jeux Mathematiques (Mathematical Puzzles) Fair | Luxembourg Gardens | Miscellaneous | Montparnasse Tower | Paris Velo Rent-a-bikes | Shops and Storefronts | Toyota Showroom on Champs-Elysées