Those who dislike green should avoid this walk. Others will get lost among the great oaks of the Saint-Germain-en-Laye forest, in search of huts, clearings, and even a castle! Before discovering Poissy and its rich past. Fixed at triple gallop, with its 3.5 tonnes of prominent muscles, it welcomes us, a totem of bronze and stainless steel. Without preamble, the statue of Ptolemy reveals the specificity of Maisons-Laffitte: it is the city of the horse, strong with its hippodrome and training center. How pleasant it is to stroll through the tree-lined streets of this city with an imperial heritage, where Jean Cocteau was born! To observe its characterful stone villas... Delving into this pleasant urban fabric, a path stretches like a prelude to the woods, a major part of this stage. Also read: Here I am in this sacred refuge, the Saint-Germain-en-Laye forest (3,500 ha, 54 km of trails), delighted, ready for this great meditative bath in all shades of green, illuminated here and there by the rays of the sun. Under the fine architecture of its canopy, this forest of great oaks reveals its wide sandy avenues, its star-shaped layout designed for hunting by François I. To the imposing temperament of this domain forest, the modesty and mischievousness of numerous huts and other tents made of sticks and branches respond, shelters for children, adventurers, poets... kings? After walking for a long time, crossing clearings and asphalted roads, I am just in front of a very, very large hut - let's say a small castle: the house of Val, in yellow limestone, converted into a luxury hotel. Originally a modest hunting lodge of Henri IV, Louis XIV transformed it into a cozy forest refuge and (relatively) intimate place, far from the pressures of the court, imagined by a very young architect: Mansart. Leaving this house, I walk along part of the botanical path, in ten stations. Throughout this walk in the forest, I will alternate between stands of robust century-old oaks and groups of young, fragile saplings. Several generations of trees succeed here, revealing the damage suffered, notably during the storm of 1999. On the shores of the very peaceful Canes pond, a pocket of biodiversity, this urgency attacks me: the absolute necessity to protect these green oases against the vagaries of climate. Return to civilization: Poissy, and its wonderful whirl of history. Here is its priory, built by Philippe the Fair (14th century), a huge convent of twelve nuns, "a very sweet paradise where one is all stunned birds," according to the poetess Christine de Pisan. Of this building, destroyed after the Revolution, remain a barn, a fragment of the enclosure and its towers, the park and the entrance gate, which now houses... the Toy Museum. Further along, the house of the painter Ernest Meissonier (1815-1891), former mayor of the city, who immortalized Poissy in a handful of canvases. And the ingenious iron house (1896, Joseph Danly), fascinating large-scale Meccano game. Then, the climax of the spectacle, the wonderful collegiate church, where Saint Louis was baptized in 1214, restored by Viollet-le-Duc in the 19th century. How can one not admire its silhouette with two towers, and daydream in front of its fantastic and improbable gargoyles? The end of the journey takes place along the Seine, guarded by precarious holiday homes, some signed by Théophile Bourgeois, with their loggias, brick games, wooden panels... Here came to refresh themselves Maupassant, Turner, Pissarro, Monet, Vlaminck... An entire world swallowed by the old Poissy bridge (13th century), destroyed in 1944, of which only the piers and some arches remain. The restaurant L'Esturgeon, a haunt of artists and poets, above, testifies to this history. On the horizon, the river flows gently.