 When the French occupied, the Muslims all migrated into the interior parts of Algeria but many returned later after Abd–el-Khader was defeated.The fort, built between 1577 and 1604, The fortifications of the place were composed of thick and continuous walls of over two and a half kilometers in circumference, surmounted by strong towers spaced between them, with a central castle or kasbah where the Spanish governor established his headquarters.The fort was built with iron, wood, sand, lime and water carried up the hill through winding and difficult paths.