The Mattei family owned the buildings opposite the Ponte Cestio. By the 14th century, when this building complex was started, they already held great power in this part of Rome. There were, in fact, two branches of the family and they exercised complete control over the Tiber

One branch lived at the edge of the Ghetto, on the Campus Martius, and the other on the Trastevere side of the Tiber. The powerful Matteis sided with the Pope in the 15th century, thereby contributing to the end of secular rule in the city. They became famous for their violent family feuds and their extremely brutal crimes, some of which took place in this district.
The Matteis were finally expelled form Rome in the 16th century. On the other side of the Mattei building complex, you'll find Piazza in Piscinula. This small irregularly shaped piazza is just one of Trastevere's fascinating corners. It was named after the ruins of a swimming pool from the baths that previously existed here.