The Tower of Homage. Gibraltar's fortifications have evolved in a number of stages. In 1333 after the 3rd siege of Gibraltar the Marinid sultan Abu al-Hasan Ali ibn Othman ordered a refortification of Gibraltar with strong walls as a halo surrounds the crescent moon. The city was expanded, and a new defensive wall was built to cover the western and southern flanks, with towers and connecting passages added to strengthen them. The existing fortifications were also strengthened and repaired. The core of the city was surrounded by substantial defensive walls with tall towers topped by merlons. The only towers to survive are the Tower of Homage and two others. A Tower and section of the Moorish city wall some 500 metres (1,600 ft) long still survives to the south of the main part of the city of Gibraltar, of similar design to defensive walls in Morocco. It may have protected a settlement on the upper part of the Rock, around where the modern Queen's Road is, but this is conjecture as archaeological evidence is lacking.