San Marino (, Italian: [sam maˈriːno]), officially the Republic of San Marino (Italian: Repubblica di San Marino; Romagnol: Ripóbblica d’ San Marein), also known as the Most Serene Republic of San Marino (Italian: Serenissima Repubblica di San Marino), is a microstate in Southern Europe completely enclosed by Italy.

Located on the northeastern side of the Apennine Mountains, San Marino covers a land area of just over 61 km² (24 sq mi), and has a population of 33,562. Its capital is the City of San Marino and its largest settlement is Dogana. The capital is set at the highest point of the country on a steep mountain. San Marino’s official language is Italian, although Romagnol is the historical language and still in existence in a non-official capacity.

The country derives its name from Saint Marinus, a stonemason from the then Roman island of Rab, in modern-day Croatia. Born in AD 275, Marinus participated in the reconstruction of Rimini’s city walls after their destruction by Liburnian pirates. Marinus then went on to found an independent monastic community on Monte Titano in AD 301; thus, San Marino lays claim to being the oldest extant sovereign state, as well as the oldest constitutional republic.

San Marino’s politics are ruled by its constitution, which dictates that every six months San Marino’s parliament must elect two Captains Regent. The Captains Regent have equal powers, and are free to exercise them within the limits of the constitution and parliamentary legislation until their term expires.

The country’s economy is mainly based on finance, industry, services and tourism. It is one of the wealthiest countries in the world in GDP per capita, with a figure comparable to the most developed European regions. Its economy is considered highly stable. It has one of the lowest unemployment rates in Europe, no national debt, and a budget surplus.