Located on the Adriatic coast at the mouth of the Aterno-Pescara River, Pescara is the most populous city in the Abruzzo region and is one of the top ten economic, commercial and tourist centers on the Adriatic coast. Pescara was the birthplace of Italian novelists Gabriele D'Annunzio and Ennio Flaiano. The historic city center is located on the south shore, where once stood the Piazzaforte (fortified town), a military bulwark of the Kingdom of the Two Sicilies. In the very south part of the city, between the D'Avalos Park and the beach, there is an elegant Art Nouveau villas district designed in 1912 by Antonino Liberi (an engineer brother-in-law of D'Annunzio). Every July Pescara holds an international jazz festival: since 1969, it has been one of the most important jazz festivals in Europe, as reported by the main dedicated international magazines.