Complex sentence: The Ajyad Fortress ("Ecyad" in Turkish) was an Ottoman fort built in 1781 (1777 or 1780 according to some sources) in Mecca in order to protect the Qa'aba and Muslim shrines from invaders.
Split into simpler sentences: The Ajyad Fortress ("Ecyad" in Turkish) was an Ottoman fort built in Mecca in the late 18th Century. In 1781 (or 1777 or 1780, according to some sources), the fortress was built in order to protect the Qa'aba and Muslim shrines in Mecca from invaders.