Fort de Boutavant, Castral mound on La Tour island in the Seine, Tosny, Eure, France

Fort de Boutavant is a former castle mound on Île La Tour, an island in the Seine at Tosny, Eure. Little of the structure can be made out from the riverbank; from above, only a square of trees marks its position. Jean Mineray describes a tower, a bridge, a palisade and works on the bank of Roger IV de Tosny's domain. The island is now joined to Île Bonnet by a dried former arm of the river.

Boutavant was built around 1198, in the reign of Richard the Lionheart, as an advanced defensive element of Château-Gaillard, alongside the fort du Muret and the château de l'Île for the defence of Normandy. It was dismantled very early, in August 1202. Jean Mineray describes its military layout: a tower, a bridge, a palisade and works on the bank of Roger IV de Tosny's domain.

The name Boutavant is recorded by the toponymist Ernest Nègre in his work on the general toponymy of France. The site is attested by two chroniclers close to Richard the Lionheart, Roger de Hoveden and Raoul de Coggeshall; the latter recalls that La Tour island first belonged to the Archbishop of Rouen. Today the island is a protected ZNIEFF, joined to Île Bonnet by a dried former arm of the Seine.

The fort's remains are hard to make out from the bank at Tosny; from above, only a square of trees marks the spot on Île La Tour. The island is a protected ZNIEFF zone and now joins Île Bonnet through a dried former arm of the Seine. Approach by boat or view from the shore, since no built structure stands visible.

Boutavant had a counterpart: Boute-Arrière at Le Goulet, built by Philip Augustus on the French border, where Renaud de Dammartin was held captive. Boute-Arrière was demolished by order of Henry V of England on 8 February 1422, and its stones, with Charles IX's renewed permission in 1571, went to rebuild the Charterhouse of Bourbon-lez-Gaillon.