San Marino, one of the smallest nations in the world and the world's oldest republic still in existence, is founded by Saint Marinus.

San Marino, officially the Republic of San Marino, is a landlocked country in Southern Europe, completely surrounded by Italy. Located on the northeastern slopes of the Apennine Mountains, it is the larger of two microstates within Italy, the other being Vatican City. San Marino is the fifth-smallest country in the world, with a land area of just over 61 km² and a population of 34,042 as of 2025. Its capital, the City of San Marino, sits atop Monte Titano, while its largest settlement is Dogana, in the municipality of Serravalle.

This is a list of the world's countries and their dependencies, ranked by total area, including land and water.

A republic, based on the Latin phrase res publica, is a state in which political power rests with the public (people), typically through their representatives—in contrast to a monarchy. Although a republic is most often a single sovereign state, subnational state entities that have governments that are republican in nature may be referred to as republics.

Marinus was an Early Christian and the founder of a chapel and monastery in 301 from whose initial community the state of San Marino later grew.