The Nehaj Fortress, the symbol of Senj, was built in 1558. Pieces of the destroyed churches, monasteries and houses outside the city walls were used in its construction. The fortress is square, with corners aligned to the four points of the compass. It is 23 metres wide and 18 metres, with walls that are 2 to 3.30 metres thick. The walls taper upwards, terminating in a crown with five turrets at the corners