A distinctive type of Ottoman tower houses (singular: Albanian: kullë; Bulgarian: кули, kuli; Serbian: kуле, all meaning "towers", from Arabic ‏قَلْعَة‎‎ (qalʿa, “fort, fortress”) via Persian qulla, meaning "mountain" or "top", and Turkish kule) developed and were built in the Balkans (Albania, Bosnia and Herzegovina, Montenegro, Bulgaria, Greece, Kosovo, Macedonia and Serbia), as well as in Romania, after the Ottoman conquest in the Middle Ages by both Christian and Muslim communities. The practice began during the decline of Ottoman power in the 17th century and flourished until the early 20th century. The tower houses were typically made out of stone, rose three or four storeys, and were square or rectangular in shape. They served both military (defence, watchtower) and civilian (reside