In Osny, historic cultural sites and expansive green spaces sit side by side as distinct highlights of a stay: the Château de Grouchy, two museums and the Gothic Église Saint-Pierre-aux-Liens tell the story of the town. The Parc de Grouchy complements these discoveries with gardens, waterways and walking paths. This makes it possible to discover Osny both through its architectural and collection history and through its parkland.

Château de Grouchy and Parc de Grouchy

The Château de Grouchy is a neoclassical château dating from the late 18th century. It was listed as a site worthy of protection in 1945, and added to the supplementary inventory of historic monuments in 1990. Today, the château is a cultural center: concerts, conferences and exhibitions are held there regularly, and it also features a permanent gallery. As the program may change, it is advisable to check the latest events before your trip.

The landscaped grounds of the château include a French garden, terraces and statues, as well as a dovecote, a temple of love, a vegetable garden, an icehouse and a pond. The Parc de Grouchy covers 39 hectares and is located in the center of Osny. Large lawns alternate with wooded areas, while an extensive network of waterways further defines the grounds. The park’s varied features also make it an interesting place for a walk that is not focused solely on the château’s architecture.

The Parc de Grouchy is a place for morning jogs, relaxation and family walks. A stop at the carousel can also be part of a walk. If you prefer to plan a longer outing, Osny has almost 16 kilometers of hiking and walking paths, including routes through the Parc de Grouchy and along the banks of the Viosne. Paths also lead from the park to the hamlet of Immarmont. Check the current route before setting out.

Church and historic collections

The Église Saint-Pierre-aux-Liens is a Gothic church dating from the 13th century, built on foundations that are probably Romanesque and date from the 12th century. After its destruction during the Hundred Years’ War, it was rebuilt and consecrated in 1479. Parts of the church also have their own heritage-protection dates: the choir was added to the inventory of historic monuments in 1926, and the bell tower in 1948. During a later interior renovation, frescoes and traces of 16th-century polychromy were uncovered.

The Musée William-Thornley is located in the attic of the Château de Grouchy. Its public collection is dedicated to the post-impressionist artist William Thornley. More than 200 drawings, lithographs, watercolors and paintings are shown in rotation in temporary exhibitions; the museum also presents works by Alexandre René Véron, Jules-Jacques Veyrassat, Camille Pissarro and Edmond Eugène Duc. The museum welcomes groups by prior arrangement. To get there, you can take bus 35 from the Osny stop on line J to the Château de Grouchy stop, or walk through the Parc de Grouchy to the museum. Check current connections and routes before your trip.

Since 1999, the Musée départemental des sapeurs-pompiers has been housed in the former stables of the Château de Grouchy. Its presentation traces the development of the firefighting profession from the 18th century to the present day. A room specially intended for children houses an extensive toy collection; the oldest pieces date from the 19th century. The museum therefore offers a different focus from William Thornley’s art collection: here, the focus is on the history of firefighting and toys, while the other museum showcases the work of a post-impressionist artist.

Discover more destinations: Fosses, Theuville, Gonesse, Magny-en-Vexin, Écouen, Longuesse, Argenteuil, Saint-Gratien.

For the overview of the wider region: Val-D'oise.