Chateau de Roquebrune, Medieval castle in Roquebrune-Cap-Martin, France.

Château de Roquebrune is a medieval fortress on the summit of Roquebrune-Cap-Martin, built at the end of the 10th century by Conrad I, Count of Ventimiglia. Its square keep, the oldest surviving in France, rises 26 metres from a Tertiary puddingstone rock and has walls two to four metres thick. The walls show cannon embrasures, machicolations, arrow slits and crenellations, and a chemin de ronde circles the keep.

The fortress was built at the end of the 10th century by Conrad I, Count of Ventimiglia, as a defense against Saracen raids along the Mediterranean coast. After a fire in the early 1500s, it was rebuilt with reinforced walls and new openings designed for cannon fire to keep pace with military technology.

The castle is also called Château Grimaldi after the Grimaldi family, who held it for several centuries and introduced artillery into its defence. In the 15th century the keep took the name of the castle, while the rest of the fortified enclosure became the village, which still keeps its medieval layout of narrow lanes covered by Romanesque vaults.

Entry involves steep, narrow stairs that are sometimes dark, so wear sturdy shoes with good grip. Early morning or late afternoon visits work best when fewer visitors are present and sunlight streams through the openings more directly.

The reception hall's vault collapsed in a fire in 1506; Augustin Grimaldi restored it in 1528 with a panelled ceiling and a cross-mullioned window. Cannonballs from the Duke of Guise's guns set it alight again in 1597, and the ceiling was never rebuilt, so the room still shows the fire's mark.