Karlovac is a city in central Croatia with population of 46,827 acording to the 2011 census. Karlovac was built from scratch in 1579 as a city-fortress in order to strengthen Austria's southern defences against Ottoman invaders. Fortress was built in a shape of six pointed star with bastions and moats, and it was named Karlstadt or Carlstadt ("Charles's Town") after Archduke of Austria Charles II.