Château d'Aveny, 18th-century château in Dampsmesnil, France

The château d'Aveny stands at the hamlet of Aveny in Dampsmesnil, Vexin-sur-Epte, built on the foundations of an 11th-century fortified house. Its main block runs 75 metres long and 5 metres wide, with a cream stone facade, a steep slate roof and a squared dome above the central entrance. Its design, though 18th-century, follows 17th-century models and recalls the facade of the château de Cheverny.

The château was originally owned by the Marquis de Broglie and purchased in 1778 by J-B-C Alain de Fayet, who undertook major restoration work through 1794. This period of transformation shaped the property into the residence it remains today.

The château's name comes from the hamlet of Aveny where it stands, and the nearby bridge over the Epte, built 1744–1746 by the engineer Martinet, links the Val-d'Oise and Eure departments. Weddings have long been held here: the earliest recorded, on 24 April 1800, united Amélie-Honorine de Fayet with Ange-Guillaume Aubourg, comte de Boury. Since its 2022 reopening the house hosts weddings, seminars and private events.

The château is a private venue hosting weddings, seminars and private events since its reopening on 2 June 2022, so visits are not open to the public on a drop-in basis. The 220 m² first-floor reception gallery was renovated in the winter of 2021–2022. Opposite the château, the Pont d'Aveny over the Epte, built 1744–1746 by the engineer Martinet, links the Val-d'Oise and the Eure.

The main block of the château is 75 metres long but only 5 metres deep, an unusually thin plan for a building of this size. Its facade is said to recall that of the Château de Cheverny, built in the mid-17th century, although Aveny dates from the 18th.