As the capital of the Ajoie, it has been important since the 11th century due to its strategic location. Already at that time, there were two churches, and the town subsequently became part of the domains of the Counts of Ferrette and the Lords of Montbéliard, before coming under the control of the Bishop of Basel in 1271.

In the course of time, the town was increasingly influenced by the Church, and after the Reformation it became the residence of the prince-bishops of Basel until 1792. The historical centre of Porrentruy, which is naturally protected by the river bifurcation, has an elongated layout, with the Faubourg spread out at the foot of the castle. Among the few vestiges of the old fortifications, the ‘Porte de France’, built in 1563, stands out. The parish church of St. Peter, a Gothic basilica built in the mid-14th century, is one of the city’s main places of worship. To the east of the old town is the church of St. Germain, dating back to the early 13th century, with its nave extended and frescoed in 1698. Further south, the former Jesuit church is now used as a lecture hall for the cantonal school. Porrentruy Castle, which dominates the town, preserves the Réfouse tower, an early 13th century building. At the end of the 16th century, Bishop Christoph Blarer had the Residence, the Chancellerie and the Tour du Coq built, the latter decorated with the rooster, symbol of the bishop.

Porrentruy’s town hall, located along the rue du Marché, has a façade that mixes elegant French architecture with the lively elements of southern German Baroque. Another example of this stylistic fusion is the old hospital, built between 1761 and 1765, which today houses a museum with a modest collection of local history and a pharmaceutical collection. Also near the town hall is the Schweizerbrunnen, a fountain from 1518 depicting a wild boar, an animal that appears in the town’s coat of arms. Finally, the botanical garden of the cantonal school, founded in 1795 by the revolutionary Lémane, adds another point of interest to the town.