Work on the wall started in 500 BC during the rule of the first Chinese emperor, [[Qin Shi Huang]], connecting many older walls which were constructed by individual pre-unified Chinese states to keep out northern barbarians. Most of the work was done during the [[Ming Dynasty]]. <ref>Susan Wise Bauer, ''The History of the Ancient World''</ref>At regular intervals towers were built; they originally functioned purely as watchtowers, but later on they were modified to include [[cannon]]s.<ref>http://factsanddetails.com/china.php?itemid=27&catid=2&subcatid=1</ref> | Work on the wall started in 500 BC during the rule of the first Chinese emperor, [[Qin Shi Huang]], connecting many older walls which were constructed by individual pre-unified Chinese states to keep out northern barbarians. Most of the work was done during the [[Ming Dynasty]]. <ref>Susan Wise Bauer, ''The History of the Ancient World''</ref>At regular intervals towers were built; they originally functioned purely as watchtowers, but later on they were modified to include [[cannon]]s.<ref>http://factsanddetails.com/china.php?itemid=27&catid=2&subcatid=1</ref> |