San Marino, a landlocked republic of 61 square kilometres on the slopes of Monte Titano, an enclave in Italy between Emilia-Romagna and the Marche and about 13 kilometres from the Adriatic, is made of nine castelli, and people have lived around its limestone ridge since Neolithic farmers lost a polished stone axe-hammer at San Giovanni sotto le Penne about 5000–4000 BCE. Bronze Age and Villanovan communities left traces at Casole, Castellaro and nearby Verucchio, Umbri, Etruscans and Gallic Senones held the hills, and from 268 BCE Rome ruled them from the colony of Ariminum, today Rimini. Tradition says that on 3 September 301 the Dalmatian stonemason Marinus, who had come from the island of Rab to work on the walls of Rimini, founded a Christian community on the mountain; the first historical trace is a monk on the Titano recorded about 511, and the oldest document of the republic is the Placito Feretrano of 20 February 885. Ostrogoths, Byzantines of the Exarchate of Ravenna and Lombards ruled the region, and after the Donation of Pepin in 756 the surrounding lands passed to the popes.

The community of Monte Titano was governed by the Arengo, the assembly of the heads of families, and defended by the Guaita tower; in 1243 the consuls Filippo da Sterpeto and Oddone Scarito are the first known predecessors of the Captains Regent. The first statutes are mentioned in 1253, the earliest surviving ones date from 1295–1302 and replaced the consuls with a Captain and a Defender, and in 1351 the bishop of Montefeltro released the commune from its feudal ties. The Great and General Council took over most powers of the Arengo, and the republic survived between the Malatesta of Rimini and the Montefeltro of Urbino. In the war of 1460–1462 San Marino joined Pope Pius II and Federico da Montefeltro against Sigismondo Malatesta, and the Patti di Fossombrone of 27 June 1463 gave it Fiorentino, Montegiardino, Serravalle and Domagnano, while Faetano joined of its own accord; its nine castelli have not changed since. Cesare Borgia occupied the republic for some months in 1503, the Statutes of 1600 and the protection treaty of 1602, in force from 1631, secured its independence under the Holy See, and Cardinal Alberoni’s occupation of 17 October 1739 ended on Saint Agatha’s Day, 5 February 1740.

Napoleon offered to enlarge the republic in 1797, and Captain Regent Antonio Onofri politely declined; the Congress of Vienna confirmed its independence in 1815. The republic sheltered Giuseppe Garibaldi and his legion on 31 July 1849, made Abraham Lincoln an honorary citizen in 1861, signed a treaty of friendship with the new Kingdom of Italy in 1862, issued its first coins in 1864 and stamps in 1877, and inaugurated the Palazzo Pubblico in 1894. After the Arengo of 25 March 1906 an elected Grand and General Council replaced the self-perpetuating oligarchy; San Marino stayed neutral in the First World War, the Sammarinese Fascist Party of Giuliano Gozi ruled from 1923 to 1943, and the railway from Rimini opened in 1932. In 1944 the neutral republic sheltered more than 100,000 refugees, was bombed on 26 June, was entered by German forces on 13 September and was freed in the Battle of San Marino of 17–20 September. A Communist–Socialist coalition governed from 1945 until the Fatti di Rovereta of 1957.

Christian Democrat and left-wing coalitions have alternated since 1957. Women won the vote in 1959 and the right to stand in 1973, the Declaration of Citizens’ Rights was approved in 1974, Maria Lea Pedini-Angelini became the first woman Captain Regent in 1981, and San Marino joined the Council of Europe on 16 November 1988 and the United Nations on 2 March 1992. The euro replaced the lira in 2002, UNESCO inscribed the Historic Centre of San Marino and Mount Titano in 2008, and the banking scandals of 2009 and 2014–2017 led to tax and banking reforms. The population, 12,800 in 1950, was 34,045 in 2025. Association talks with the European Union opened in 2015 and concluded on 12 December 2023, and the EU Council authorised the signature of the agreement on 16 July 2026. San Marino is still headed by two Captains Regent, elected every six months and invested on 1 April and 1 October, at present Gerardo Giovagnoli and William Casali, with no prime minister: Luca Beccari has been Secretary of State for Foreign and Political Affairs since 8 January 2020. Explore the eight ages below through selected events from the timeline.