The patron of Isola del Liri is the Madonna of Loreto, celebrated on 10 December. According to tradition, the Madonna saved the town from the plague outbreak that struck the area in 1654.
The town holds the Church of San Lorenzo Martire and the Torre Marica, as well as the Castello Boncompagni-Viscogliosi and the famous vertical Waterfall of Isola del Liri.