San Marino, officially the Republic of San Marino and also known as the Most Serene Republic of San Marino (Italian: Serenissima Repubblica di San Marino), is an enclaved microstate surrounded by Italy, situated on the Italian Peninsula on the north-eastern side of the Apennine Mountains. Its size is just over 61 km2 (24 sq mi) with an estimated population of over 30,000. Its capital is the City of San Marino.