The interior is a beautiful little space with a single nave and two side aisles, separated by ancient columns originally taken from assorted local Roman temples and used in the 5th century church. Frescoes on the walls of the nave, by Pietro da Cortona (left side) and Agostino Ciampelli (right side), show Scenes from the Life of St Bibiana. Made in 1624, they were ordered after Cardinal Francesco Barberini, Pope Urban VIII's nephew, had discovered da Cortona's talent.