Sérrai (sâ´râ), Siris (sī´rĬs), or Serres (sĕr´əs), Lat. Serrae or Serrhae, city (1991 pop. 50,390), capital of Sérrai prefecture, NE Greece, in Macedonia. It is a trade center for tobacco, grain, and livestock. Textiles and other light manufactures are produced. The city was fortified under the Byzantine Empire and in the 14th cent. became a capital of Czar Stephen Dušan of Serbia. Sérrai was held by the Ottoman Empire from 1383 to 1913, when it passed to Greece. The city was occupied and damaged by Bulgaria in both World Wars.