 The first recreational parks, for their part, were built during the Second French Empire.The étang Saint-Nicolas, made by a sluice on a small river, the Brionneau, was protected as early as 1936.The Jardin du Mail ("Mall Garden"), an esplanade situated outside the ring boulevards, was built between 1820 and 1880 on the former Champs de Mars (Fields of Mars, a place where the garrisons used to train and parade).