The patron feast of Sassello is the Beheading of Saint John the Baptist, celebrated on 29 August. His church, much older than the parish church of the Santissima Trinità with which it forms the parish community of the main village, was erected in the 11th century and is the town's first place of worship, although repeatedly remodelled over the centuries it lost its original appearance. It holds 16th- and 17th-century paintings, along with sculptures of the Genoese school, including a statue by Anton Maria Maragliano.
The parish church of the Santissima Trinità, built between 1654 and 1725 in the historic centre, is preceded by a colonnade and houses fine 18th-century frescoes by Paolo Gerolamo Brusco together with several paintings of the 17th- and 18th-century Genoese pictorial school. The town, also known for its traditional 19th-century soft amaretto biscuit, also celebrates the Corpus Domini flower festival, when the streets of the historic centre are decorated with petal designs inspired by religious subjects.
