The Basilica Julia is located in the southernmost area of the Forum. It consists of a rectangular roofed hall which served as a social and legal meeting-place. The basic unit of construction is the arch. Instead of being carried on columns, the second storey and ceiling were carried on cruciform piers. The porticoes were vaulted, and the central hall was timber-roofed. The building materials were primarily tufa, travertine, and brick-faced concrete with marble veneers.
Vitruvius said "Basilicas should be constructed on a site
adjoining the forum, and in the warmest possible quarter, so that
business men may gather in them without being troubled by the
weather. And their breadth should be not less than one-third, nor
more than half, their length, unless the nature of their site
prevents it and forces the proportions be a different shape. When the
site is longer than necessary, the committee rooms are to be placed
at the end of the basilica, as they are at the Basilica Julia at
Aquileia [a village near Venice]." (Book V.4)
The site was formerly occupied by the house of Scipio Africanus. The Basilica Sempronia was built on the site by the Father of Tiberius and Gaius Gracchus, who was married to Cornelia, the daughter of Scipio Africanus. circa 170 BCE. A series of shops or offices connected to the Basilica Sempronia were known as the Tabernae Veteres, and they lined the Sacred Way. Incorporated into the foundations of the Basilica was the Cloaca Maxima, which ran along the Vicus Tuscus, with the Temple of Castor and Pollux on its East and the Basilica on its West.
Caesar bought the land under the Tabernae Veteres and the Basilica Sempronia and then leveled the ground and began construction of the Basilica Julia in 54 BCE. It was dedicated in 46 BCE while still unfinished, in commemoration of the victory at Thapsus on September 26th, together with the Forum Julium and the Temple of Venus Genetrix: thus Caesar considered this building as a part of the first of the imperial fora. In addition, Caesar had begun rehabilitation of the Basilica Aemilia, the Curia, and the Rostra in an effort to bring order to the haphazard development of the Roman Forum.
Caesar (54-46 BCE) Foundations, tufa and travertine. Cic.
Att. 4.16.8, Augustus RG 20, Hieron, a. Abr. 1971.
Augustus (12 BCE - CE 12) Completed and dedicated it in the names of his sons Gaius and Lucius. Augustus RG 20, Cass. Dio 56.27.5, Suet. Aug. 29.4.
Carinus (284 CE) The Basilica Julia burnt down. Chron. 148.
Diocletian (305 CE) restored and rebuilt it. Chron. 148.
Refurbished under the prefect Gabinius Vettius Probianus circa 416 CE. Click here to see the text and photo of one of the five statue bases inscribed by him.
Other primary sources include Martial 6.38.6; Statius Silv.
1.1.29, Suet. Caligula 37.1, Pliny Epist. 5.9.1, Quintilian 12.5.6.
CIL 6.9709 = ILS 7509, CIL 6.9711. Marble Plan FUR pl. 21.