The patron saint of Vastogirardi is Saint Nicholas of Bari, whose mother church dominates the central part of the village, perched on a hill topped by the castle and the church complex dedicated to him. His feast falls within a three-day celebration from 1 to 3 July: the first two days are dedicated to the Madonna delle Grazie, while on 3 July the patron is celebrated, with the traditional fireworks that liven up the summer event.
Within the walls, the village remains well preserved in its original defensive function, with cylindrical towers embedded in the buildings. The church of San Nicola, inside the castrum, was restored by Prospero Petra, son of Giovan Leonardo Petra and a distinguished jurist, who commissioned its frescoes and was buried there: from the same family descended Cardinal Vincenzo Petra, prefect of the Congregation of Propaganda Fide and Archbishop of Damascus. In the area next to the Fonti del Trigno, Vastogirardi also hosted an important Italic temple, dated between the 3rd and 2nd centuries BC and probably dedicated to Hercules, of which only the foundations survive today: its foundations and perimeter walls were reused in medieval times to build a small church, called Sant'Angelo Indiano, whose apse perimeter is still visible and which still gives its name to the locality.
