In AD 283, the year before Diocletian became emperor, a fire destroyed the Basilica Julia, which provided him an opportunity to rebuild several important buildings, including the Curia (Senate House). In AD 303, five honorary columns carrying statues were added behind the Rostra, as can be seen in the depiction of the Rostra on the Arch of Constantine. The first major structure to be erected in the Forum since the time of Septimius Severus, they celebrated the decennalia of the Tetrarchy, which was the occasion of Diocletian's only visit to Rome as emperor. All of pink granite from Aswan, the middle, taller one carried a statue of Jupiter, the others, the four rulers of the empire (two Augusti and two younger Caesars).
One of the marble pedestals was discovered in 1547, The so-called Decennalia Base has been placed nearby on the Via Sacra. The front displays two winged victories holding a shield on which is inscribed CAESARUM DECENNALIA FELICITER, "Happy Tenth Anniversary of the Caesars." To provide symmetry, a new rostra, with a corresponding number of columns, was placed at the opposite end of the Forum in front of the Temple of Divine Julius. This shortened the Forum square and shifted emphasis to the newly restored Basilica Julia and Senate House. Joining both rostra were seven honorary columns, pictured above, that ran in front of the Basilica. A single larger column (which later was reworked as the Column of Phocas), presumably honoring Diocletian, himself, was placed on an axis with the Argiletum, the throughfare that ran along the Curia which now became the main approach to the Forum.
