San Marino, officially the Republic of San Marino (Repubblica di San Marino), 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 northeastern side of the Apennine Mountains. Its size is just over 61 km2 (24 sq mi) and has an estimated population of about 32,000. Itscapital is the City of San Marino and its largest city is Dogana. San Marino has the smallest population of all the members of the Council of Europe.

San Marino claims to be the oldest surviving sovereign state and constitutionalrepublic in the world, as the continuation of the monastic community founded on 3 September 301, by stonecutter Marinus of Arba. Legend has it that Marinus leftRab, then the Roman colony of Arba, in 257 when the future emperor Diocletianissued a decree calling for the reconstruction of the city walls of Rimini, which had been destroyed by Liburnian pirates.

San Marino is governed by the Constitution of San Marino (Leges Statutae Republicae Sancti Marini), a series of six books written in Latin in the late 16th century, that dictate the country’s political system, among other matters. The country is considered to have the earliest written governing documents (constitution) still in effect.

The country's economy mainly relies on finance, industry, services and tourism. Despite having an extremely small economy for a nation state, it is one of the wealthiest countries in the world in terms of GDP (per capita), with a figure comparable to the most developed European regions. San Marino is considered to have a highly stable economy, with one of the lowest unemployment rates in Europe, no national debt and a budget surplus.

 It is the only country with more vehicles than people.