Osny: Château de Grouchy, museums and park

In Osny, Château de Grouchy, Église Saint-Pierre-aux-Liens and two museums with different focuses offer insights into cultural history. Parc de Grouchy adds green spaces and paths to the town’s character. You can plan your stay around your interests in architecture, art, firefighting history or spending time outdoors.

A château and a church: two historical timelines

Château de Grouchy is a Neoclassical château dating from the late 18th century. It was listed as a protected site in 1945 and added to the supplementary inventory of historic monuments in 1990. The château serves as a cultural centre, regularly hosting concerts, conferences and exhibitions; it also has a permanent gallery. Check the current schedule before your visit.

Église Saint-Pierre-aux-Liens tells a different story of construction. The Gothic church was built in the 13th century, probably on 12th-century Romanesque foundations. After being destroyed during the Hundred Years’ War, it was rebuilt and consecrated in 1479. Its heritage listings also refer to different parts of the building: the choir was added to the inventory of historic monuments in 1926, and the bell tower in 1948. A later interior renovation revealed frescoes and traces of 16th-century polychromy.

Two museums with different focuses

The Musée William Thornley is located in the attic of Château de Grouchy. Its public collection is devoted to the Post-Impressionist artist and displays a selection of his works. Rotating exhibitions feature more than 200 drawings, lithographs, watercolours and paintings in turn. William Thornley is underrepresented in national collections. The museum also displays works by Alexandre René Véron, Jules-Jacques Veyrassat, Camille Pissarro and Edmond Eugène Duc. Groups are welcomed by prior arrangement.

The Musée départemental des sapeurs-pompiers has been housed in the former stables of Château de Grouchy since 1999. Its collection ranges from hand pumps and motor pumps to vehicles, uniforms and firefighting equipment. Children have a dedicated room featuring an extensive collection of toys; the oldest pieces date from the 19th century. The two museums therefore offer different perspectives: one focuses on artworks, the other on firefighting history and toys.

Green spaces and paths in Osny

Parc de Grouchy is a 39-hectare green space in the centre of Osny. The landscaped grounds of Château de Grouchy include a formal French garden, a dovecote, terraces and statues, as well as a temple of love, a vegetable garden, an ice house and a pond. Large lawns, wooded areas and an extensive network of waterways define other parts of the park. Designed garden features and open green spaces sit side by side.

Parc de Grouchy is a place for morning jogs, relaxation and family walks; a stop at the carousel can also be part of a stroll. For longer outings, Osny has almost 16 kilometres of walking and hiking trails. These include paths through Parc de Grouchy and along the banks of the Viosne. Paths from the park also lead to the hamlet of Immarmont. If you are planning a particular route, check the latest route information in advance.

Getting to the Musée William Thornley

To reach the Musée William Thornley, take bus 35 from the Osny stop on Line J to the Château de Grouchy stop. Alternatively, you can walk to the museum through Parc de Grouchy. Check current transport connections before setting out.

Discover more destinations: Cergy, Herblay, Saint-Gratien, Roissy-En-France, Magny-en-Vexin, Saint-Brice-Sous-Forêt, Seraincourt, Ronquerolles.

See the broader travel overview: Val-D'oise.