Nizwa was the captial of Oman in the 6th and 7th century. In the 17th century an imposing fort was built by Sultan Bin Saif Al Ya'ribi. In the early 1950s the large round tower of the fort was bombed and the British Royal Air Force was requested to assist in the supression of the revolt. Since the 1970's, Nizwa has become a more modern city although maintaining strong traditional architecture. http://wikitravel.org/en/Nizwa