The patron saint of Ariccia is Saint Apollonia, celebrated on 9 February.
During the 1656 plague, Ariccia was spared the scourge, partly due to its relative isolation: the people of Ariccia, however, attributed the grace to the Madonna di Galloro, and a solemn feast began to be celebrated at the sanctuary of Santa Maria di Galloro, initially fixed for the first or second Sunday of the month. From 1668, when Pope Clement IX instituted the feast of the Immaculate Conception, the date was moved to 8 December: this event, still celebrated today, takes the name «festa della Signorina». The town also holds the Collegiate church of Santa Maria Assunta and Palazzo Chigi.
