sentences:  The longest current reigning female monarch is Elizabeth II, who is the Queen of the United Kingdom and other Commonwealth realms, and is a constitutional monarch.She has been Queen of the United Kingdom, Australia, Canada and New Zealand, since February 6, 1952, but all of the other countries she is at present queen of had yet to gain independence at the time of her accession.The longest-serving non-royal head of state in the 20th and 21st centuries was Fidel Castro, who held the titles of Prime Minister of Cuba, First Secretary of the Integrated Revolutionary Organizations, First Secretary of the Central Committee of the United Party for the Socialist Revolution of Cuba, First Secretary of the Central Committee of the Communist Party of Cuba, President of the Council of State, and President of the Council of Ministers of the Republic of Cuba.