Château de Quart, Medieval castle on rocky slope in Quart, Italy.

Château de Quart is a medieval fortress located on a steep mountain slope near Aosta that consists of multiple fortified structures. These buildings follow the natural contours of the hillside and form a connected complex around a central courtyard.

The castle's oldest part was built around 1185 by Jacques de la Porte de Saint-Ours, founder of the Lords of Quart, on a spur controlling the Dora Baltea trade route. When the last male heir, Henri de Quart, died in 1378, the estate passed to the House of Savoy, which kept it until 1550. It then changed hands repeatedly: Laschis, Balbis, Coardo and from 1612 the Perrone di San Martino, who gave it to the commune of Quart in 1800.

The castle appears on Quart's coat of arms and banner. Below it lies the Vollein hill, where a Neolithic necropolis was found in 1968, among the oldest traces of settlement in the Aosta Valley. A trail from the castle passes prehistoric cup-marked stones and didactic panels on flora, fauna, geology and finds, leading to the hermitage of Blessed Emeric with a picnic area.

The castle is closed to the public during the restoration begun in September 2010, apart from rare exceptions such as the 2016 Châteaux ouverts open site. It is reached from the village of Quart by a gently climbing road from the west, ending at an esplanade where a water basin once stood. The original approach path is unusable because its bridge collapsed.

The castle's oldest part is a square keep built after 1261 on the site of an 11th-century predecessor, at the highest point of the rock. Traces of frescoes painted for Henri de Quart by Piedmontese artists survive there; they were covered with white paint around 1500 when the castle lost importance. A second fresco cycle in the great hall of the south wing dates to no later than 1557.