Square Léon Serpollet, created in 1991 on the former site of Léon Serpollet’s workshops in Paris’s 18th arrondissement, covers 1.58 ha across multiple terraced levels. Donated to the city by Madame Marzak, it honors the French industrialist and steam automobile pioneer who conducted major experiments between 1881 and 1887, inventing the flash‑steam boiler and the steam tricycle.

The garden features flowering cherry alleys, Byblazan nut trees, apple trees, maples, Siberian elms, Judas trees and Virginia tulip trees. Two small waterfalls feed a stream leading to a granite fountain basin, bordered by water lilies, irises and acid‑soil plants.

On the leisure side, the square is equipped with a playground with swings and sandpit, fitness equipment and a baby‑foot, ping‑pong tables, chess & checkers boards, basketball and football courts, boulodrome, drinking water points, a mist sprayer and picnic tables for family gatherings or casual rest.

The atmosphere is peaceful and family‑friendly, favored by local residents, children playing, casual athletes, walkers, readers or anyone seeking a green oasis in the city. In summer, it hosts events like open‑air library readings or star‑gazing evenings.

A glass memorial stele commemorates young Jewish children from the 18ᵉ arrondissement deported during World War II, adding a poignant historical element to this recreational space.

Practical info: accessible by metro line 12 (Lamarck‑Caulaincourt or Jules Joffrin), main entrance at 25 rue des Cloys, secondary access via rue Marcadet or rue Achille‑Martinet. The garden holds the EcoJardin label; note no Wi‑Fi, no changing table or vending drinks, and pets are not permitted. It’s open daily season‑dependently: summer from 8 a.m. (9 a.m. weekends) to 9:30 p.m.; autumn until 7:30 p.m.; winter until 7 p.m. or 5:45 p.m., depending on the schedule.