"And certainly, the senate house in particular should be built above all so as to enhance the dignity of the town or city. And if this senate house is going to be square, then whatever its length, its height should be half again as much. If, on the other hand, it is to be oblong, then the length and width should be added together, and half this measure should be given over to the height of the senate house up to the level of the ceiling coffers."
Vitruvius, De Architectura (V.2.1)
Begun by Caesar to replace the old Curia Hostilia and called the Curia Julia in his honor, the new Senate House was completed by Octavius in 29 BC (who, two years later, would be given the title of Augustus) and restored by Domitian in AD 94. After the fire of AD 283, the Curia was reconstructed by Diocletian. The present building was converted to a church in AD 630, which accounts for the state of preservation. In the mid seventeenth century, the bronze doors were removed to serve as the portals of the basilica of San Giovanni in Laterano (St. John Lateran). In 1937-1938, to celebrate the two thousandth anniversary of the birth of Augustus, Rome's first emperor, Mussolini restored the Curia as part of larger urban work projects.
A coin issue of AD 28 shows the Senate house originally as having a colonnaded porch (one still can see where it was fitted to sockets below the three large windows) with a statue of Victory crowning the pediment and two other acroteria at the corners, each holding a sceptor or spear and patera (libation bowl).
Following the prescription of Vitruvius, the height of the Curia is half the sum of its length and width, the ratio which he deemed correct for proper acoustics.
Although the walls now are bare, the marble floor is a beautiful example of opus sectile, in which pieces of colored stone are fitted together in figured patterns or geometric shapes. Just visible on the steps to the sides are two large marble reliefs (anaglyphs) or parapets (plutei) which were found in the Forum and may have decorated the Rostra as a balustrade. The porphyry statue in the background was found behind the Curia and is thought to belong to a monument honoring Trajan.
Reference: Vitruvius: Ten Books on Architecture (2001) translated and edited by Ingrid D. Rowland and Thomas Noble Howe. The drawing comes from Rome: An Oxford Archaological Guide (1998) by Amanda Claridge.
