The entablature which surmounts these arches is badly designed and executed, the projections over the columns being far too heavy. Upon the attica above the entablature there are the traces of nails on the corner pilasters which seem to have borne some military ensigns. The whole central space of the attica is occupied by a long inscription formerly inlaid, as appears from the rivets, with metal. Upon a coin of Severus giving a representation of the arch, a chariot with six horses is shown standing over the attica, and on the four corners were equestrian statues. From the inscription it appears that the arch was built in the year A.D. 203. The repetition of the title Parthicus, points to the Parthian campaigns of Severus. In the fourth line the name of Geta and his titles have been erased, as in other ruins of the same date, and the words OPTIMIS FORTISSIMISQUE PRINCIPIBUS inserted in their place. In the middle ages the tower of a church called SS. Sergio e Bacco was built upon the top of this arch, but was removed in 1536 on the entry of Charles V. by command of Pope Paul III. [Sidenote: Ruins under the road across the end of the Forum.] Near the Arch of Severus, and also between the temple of Saturn and the corner of the Basilica Julia, the modern road runs over archways. Under the archways some substructions of large peperino stones and other forms of building have been disclosed. These may have belonged to pedestals upon which statues were placed, or in the case of those near the arch of Severus to the later Rostra and Græcostasis, and in the case of those near the corner of the Basilica Julia to the Arch of Tiberius. The round pedestal which stands near the Arch of Severus was possibly the pedestal of the Miliarium Aureum, as it is not strong enough to bear the weight of a heavy statue.[62] A representation of the Rostra of the Empire which may have stood here is given in the relief on the face of the Arch of Constantine, which looks towards the Coliseum, where three arches are seen, corresponding to the Arch of Severus on the right, and one arch corresponding to that of Tiberius on the left. Constantine is shown in this bas-relief addressing the people from the rostra. [Sidenote: The Carcer.] Under the church of S. Giuseppe dei Falegnami, which stands near the Arch of Severus, are two chambers, which are always shown as the ancient prison of Rome, said to have been first built by the King Ancus Martius, and then rebuilt or enlarged by Servius Tullius. The upper of these two chambers is of an irregular shape, but the lower is constructed in a conical form by the gradual projection of the stones forming the sides. This mode of building an arch is of very early date, before the introduction of the principle of the round arch, and is found in the oldest tombs of Etruria, and in well-houses at Tusculum and Cære.[63]