The Church of San Martino was founded in 1332 by Bonifacio della Gherardesca. The flanks and apse of the large brick building, remodelled in the 17th century, are decorated with pilaster strips and hanging arches enlivened by ceramic basins whose originals are exhibited at the Museum of San Matteo.
The interior preserves fine 14th-century frescoes by Giovanni di Nicola, Antonio Veneziano and Cecco di Pietro. From the same century is also a beautiful relief by Andrea Pisano representing ''St. Martin and the Poor Man'', originally set in the façade. Also worthy of mention is a crucifix by Enrico di Tedice, dating from the latter half of the 13th century. The high altar preserves the remains of St. Bona, a native of Pisa and patron saint of air hostesses.