San Marino, officially the Most Serene Republic of San Marino and also known as the Republic of San Marino, is the oldest existing representative republic and the European state with the smallest population, apart from Vatican City. It is the larger of the two microstates surrounded by Italy. Located on the northeastern side of the Apennine Mountains, it is th…San Marino, officially the Most Serene Republic of San Marino and also known as the Republic of San Marino, is the oldest existing representative republic and the European state with the smallest population, apart from Vatican City. It is the larger of the two microstates surrounded by Italy. Located on the northeastern side of the Apennine Mountains, it is the fifth-smallest country in the world, with a land area of just over 61 km² and a population of 33,642, as of 2023.