Serravalle (Romagnol: Saravâl) is one of the nine of San Marino. It has a population of 11,226 inhabitants (of whom 2,000 are of foreign origin) and an area of 10.53 km<sup>2</sup> (4 sq. mi.). It is both the most populated and densely populated municipality in San Marino, and contains its largest settlement (Dogana). Serravalle is located on the edge of the Apennine Mountains.
The town borders on Sammarinese municipalities of Domagnano and Borgo Maggiore and the Italian municipalities Verucchio, Rimini and Coriano. Serravalle counts a surrounding quarter named Galazzano, where the weather station and an industrial area are located. Serravalle has San Marino's northernmost and lowest elevated points. The outer edge of Serravalle is about from central Rimini and the Adriatic Sea.
Serravalle recorded a temperature of on 3 and 9 August 2017, which is the highest temperature to have ever been recorded in San Marino.
Serravalle contains eight : CÃÂ Ragni, Cinque Vie, Dogana, Falciano, Lesignano, Ponte Mellini, Rovereta, and Valgiurata.
Serravalle has a humid subtropical climate (Köppen: Cfa).
First mentioned in a 962 document, in medieval times this town was called Castrum Olnani (later Olnano), meaning "the village of the elm trees". Serravalle attached to San Marino in 1463, during the last territorial expansion of the Republic.
In the Rimini earthquake on 16 August 1916, several houses in Serravalle collapsed. Two houses were damaged in the earlier earthquake on 17 May 1916.
Serravalle is twinned with: