Saint Ursanne (population approximately 1,000) is a city and a former municipality of the district of Porrentruy in the canton of Jura, Switzerland which has preserved its medieval character. The city contains many historical curiosities, including collegiate churches, a cloister, ruins of a castle, and a hermitage. The River Doubs makes a loop by Saint-Ursanne before flowing into France. Since 2009 Saint Ursanne is a part of the new municipality Clos du Doubs. Additionally, the city is famous for the medieval festival which it organizes each summer.
Its name refers to Saint Ursicinus, a seventh-century monk who built a monastery here.