San Marino, 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 small country (and a European microstate) in Southern Europe enclaved 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.

San Marino is a landlocked country but the northeastern end is within 10 kilometres (6.2 mi) of the Italian city of Rimini on the Adriatic Sea. The nearest airport is also in Italy. The country's capital city, the City of San Marino, is located atop Monte Titano, while its largest settlement is Dogana within the largest municipality of Serravalle. San Marino's official language is Italian.

The country derives its name from Saint Marinus, a stonemason from the then-Roman island of Rab in present-day Croatia. Born in AD 275, Marinus participated in the rebuilding of Rimini's city walls after their destruction by Liburnian pirates. Marinus then went on to found an independently ruled 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.

Uniquely, San Marino's constitution dictates that its democratically elected legislature, the Grand and General Council, must elect two heads of state every six months. Known as captains regent, the two heads of state serve concurrently and hold equal powers until their term expires after six months.

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.

San Marino Historic Centre and Mount Titano covers 55 ha, including Mount Titano and the historic centre of the city which dates back to the foundation of the republic as a city-state in the 13th century. San Marino is inscribed as a testimony to the continuity of a free republic since the Middle Ages. The inscribed city centre includes fortification towers, walls, gates and bastions, as well as a neo-classical basilica of the 19th century, 14th and 16th century convents, and the Palazzo Publico of the 19th century, as well as the 18th century Titano Theatre. The property represents an historical centre still inhabited and preserving all its institutional functions. Thanks to its position on top of Mount Titano, it was not affected by the urban transformations that have occurred from the advent of the industrial era to today.

San Marino is one of the world’s oldest republics and the only surviving Italian city-state, representing an important stage in the development of democratic models in Europe and worldwide. The tangible expressions of this long continuity as the capital of the Republic, its unchanged geo-political context and juridical and institutional functions, is found in the strategic position on the top of Mount Titano, the historic urban layout, urban spaces and many public monuments. San Marino has a widely recognised iconic status as a symbol of a free city-state, illustrated in political debate, literature and arts through the centuries. The defensive walls and the historic centre have undergone changes over time that include intensive restoration and reconstruction between the end of the 19th century and the first decades of the 20th century, a process that can be considered to be part of the history of the property and reflects changing approaches to conservation and presentation of heritage over time.

San Marino and Mount Titano are an exceptional testimony of the establishment of a representative democracy based on civic autonomy and self-governance, with a unique, uninterrupted continuity as the capital of an independent republic since the 13th century. San Marino is an exceptional testimony to a living cultural tradition that has persisted over the last seven hundred years.

The Historic Centre of San Marino on Mount Titano includes all the elements which constituted the foundations of this identity and during the medieval period of the Italian city-states. Many elements of the historic centre have been preserved or, if renewed, form part of a long tradition. The interventions carried out during the 20th century could be seen as affecting the integrity, but are also a part of the history of the property. There is a high degree of authenticity of the location and setting of the city of San Marino. With regard to functions and uses, there is a continuity related to the role of the historic city as capital of the small state. Restoration and reconstruction works carried out under the direction of Gino Zani may be considered as a part of the history of the property and an application of the theoretical principles stemming from the Romantic restoration movement. In this case, the idea of the “medievalisation” of the historic centre can be considered as an expression of national identity through the search for an idealised image of the historic centre.

The protection of the property is adequate, although there are a considerable number of legal protective instruments and more specific legal instruments regarding protection of the built heritage and of the surrounding landscape are required. The historic centre has not been subject to major interventions after the 1930s and the public monuments and open spaces are in a good state of conservation.

are a group of towers located on the three peaks of Monte Titano in the capital, also called San Marino, they are depicted on both the national flag and coat of arms.