Castellar is a locality of 2,777 acres (1,224 ha) bordering Italy and near the border between France and the Principality of Monaco. Its territory includes the Saint-Sébastien hill, on which the current village stands at an altitude of 1,217 ft (371 m). It rises from 328 ft (100 m), toward Menton, to 4,534 ft (1,382 m) above sea level. The ancient village, now reduced to ruins known as Vieux Castellar, was implanted on a rocky outcrop northeast of the current locality.