The territory of the municipality of Castellar in the Alpes-Maritimes department is oriented north-south. Adjoined to the east by the Italian border and the localities of Olivetta San Michele and Ventimiglia from north to south, it is adjacent with the municipalities of Sospel to the north, Castillon to the north-west and Menton to the west and south. Its rugged relief is formed by high hills and steep mountains dominated by the peaks of Mont Mulacié (4,350 ft / 1,326 m), Mont Razet (4,219 ft / 1,286 m), Gramondo (4,520 ft / 1,378 m) and Roc de l'Orméa (3,713 ft / 1,132 m). It is cut by the Careï, Fossan, and Albaréa watercourses and ends in the west with the Careï Valley.