"Borj el-Kebir" means Big Fortress, and it truly applies. As seen from further out on the peninsula, the city fortress is quite impressive. It dates back to 1595, while the bastions in the corners are 18th century additions. What you see inside may be disappointing, being almost completely unadorned and with a simple layout. Of the more interesting things are the inner quarters. From atop you will enjoy great views over the city, the port and the sea.