Isona i Conca Dellà Main Festival Activity · Isona i Conca Dellà, Pallars Jussà, Lleida Image of Isona i Conca Dellà, not of the place itself. The fiesta mayor of Isona i Conca Dellà is celebrated in the town that occupies the site of Aeso, a city of pre-Roman name that attained municipal status in imperial times; the present-day municipality was formed in 1970 from the merger of six villages of the Conca Dellà and is today known for the dinosaur egg sites of Basturs. Photo: Viquipèdia / Wikimedia Commons (CC BY-SA) What to see and do in Isona i Conca Dellà