The 15th-century bell tower is placed at the end of the right transept. The structure was later incorporated into the Neo-Classical monastery that covered the larger part of its body. The tall brick tower was built in Northern Italian style which was unusual at the time in Rome but probably suited the taste of the Lombard congregation. The conical spire, which was built of petal shaped clay bricks, is surrounded with four cylindrical pinnacles with conical caps. These pinnacles have two superimposed rows of blind arcades with cusped brick arches. The spire is crowned with a ball and cross finial with an added weather vane. The top part of the tower shows a strong similarity to the bell tower of the Basilica of San Zeno in Verona. The rectangular tower is articulated by stone cornices. On the top floor it has large arched windows on every side. Only damaged traces of the original stone mullions and ornamental brickwork parapets survived in the openings except on the eastern side where the mullion remained intact. This is a typical biforate window with small Tuscan pillars and a quatrefoil.