Château du Plessis-de-Vair, Medieval castle in Vair-sur-Loire, France.

Château du Plessis-de-Vair stands at Anetz in Vair-sur-Loire, Loire-Atlantique. Its pale stone facade is symmetrical: a taller central block under a steep grey slate roof with a small lantern at the peak, flanked by wings ending in pointed slate pavilions. White-framed rectangular windows, some with carved stone surrounds, line the walls, and a short double staircase between two white pillars leads to the entrance door at the end of a gravel path across the lawn. Two round towers, a dovecote and the archives survive from the 15th-century castle, while two square towers, the chapel, the orangery and the two entrance pavilions date from the 17th century.

The fortress was built in the 12th century as a residential stronghold and underwent major restructuring in the 15th century, preserving two round towers and a dovecote. Later classical additions from the 17th century shaped its current appearance.

The castle is linked to Chrétien de Troyes, who came to Nantes for the coronation of Duke Conan IV in 1158 and is said to have drawn inspiration here. In his Perceval, the Grail castle is called the "château de Verre" or "château aux 500 fenêtres", and the site also bears the name "château de la Merveille".

The château stands at Anetz in Vair-sur-Loire, at the end of a straight gravel path across a lawn. The site has been restored in several campaigns, including the four 15th- and 17th-century towers, the chapel windows and the moat walls. Visits are possible through the events and openings organised by the owners, the Allizon family since 2011.

In 1518 Claude of France, pregnant with the future Henry II, stayed at Vair for two months while Francis I travelled, and Anne Boleyn, then her lady-in-waiting, was with her. The future queen of England thus spent part of 1518 at this house in Anetz.