The Church of St. Siffred is a former cathedral church of the Catholic diocese, the first bishop of which was St. Siffred. The church was built in the 15th century at the insistence of the Pope Benedict. Address: Place Saint-Siffrein, 3. Admission is free. One of the relics kept in the cathedral is the nail with which Christ was nailed to the cross. Four such nails are known, two of them are in Italy, and two are in France - in the Notre Dame Cathedral and the church of the city of Carpentras. The nail from Carpentra was no longer preserved in the form of a nail - from a priceless relic, the mother of the Byzantine emperor Constantine - Elena ordered to forge a bit for her son's horse, which were supposed to protect him on the battlefield.→