The bell tower is also now altered with clock removed and arches opened. The bell tower is the tallest medieval belfry in Rome. The Fontana dei Tritoni is in the foreground (by Carlo Bizzacheri, 1715)

The church was built in the 6th century over the remains of the Templum Herculis Pompeiani in the Forum Boarium and of the Statio annonae, one of the food distribution centres of ancient Rome. A substantial restoration was accomplished in 1118-1124 under Alfanus, camerarius of Pope Callixtus II. Has an exceptionally well preserved early medieval choir enclosure and its very fine Cosmatesque pavement. Its bell tower is the tallest medieval belfry in Rome. The current interior has a nave with two aisles: these are divided by four pilasters and eighteen ancient columns. In the side walls some of the old columns of the Statio Annonae are included. Baroque additions to the church, including a facade by Giuseppe Sardi were removed in a restoration of 894-1899.