Inside the church, there is a single nave, even though the façade, vaunting three large marble arches, makes you think differently. One curious element is the floor, which is spread across various levels because of the terrain the church was built on. There is also a large number of painted altars, nine in total: the most important is the one depicting the Annunciation, which is attributed to the Lucca-based painter Taddeo Zacchia.
The building is also tied to a particular person in history: this is where father Eugenio Barsanti celebrated his first services, known along with Felice Matteucci as the inventor of the internal combustion engine. For a period, there was a commemorative bust on display inside the church, but it has since been moved to Santa Croce in Florence, where the man is buried.