San Sebastiano in Vallepiata is an ancient church facing piazzetta della Selva, in the Contrada della Selva.
Church construction began in 1492 and completed in 1656. The interior is frescoed by 16th century painters, depicting Dream of St Irene by Stefano Volpi, a Glory of St Sebastian and a Virtue and Angels by Sebastiano Folli, a Stories of St Sebastian by Pietro Sorri and Rutilio Manetti. On the main altar there is a Spoliation of Christ by Luigi Ademollo, and a 15th-century Crucifix, which legend holds was donated to the Compagnia di San Giovanni Battista della Morte (Company of St John the Baptist of the Death) by St Bernard himself.