The first set of walls to enclose the city was built in the 9th century. In the middle of the 14th century the 1.5m-thick defence was fortified with 15 square forts. The threat of attacks from the Turks in the 15th century prompted the city to strengthen the existing forts and add new ones, so that the entire old town was contained within a stone barrier 2km long and up to 25m high.  Regardless of whether you are visiting Dubrovnik for the first time or the 100th, the sense of awe never fails to rise when you set eyes on the beauty of this old town.  Although the shelling of Dubrovnik in 1991 horrified the world, the city has bounced back with characteristic vigour to enchant visitors again.