The Basilica Julia began construction in 54 BC, but was only completed a few years before it was burnt down during 9 AD. Julius Caesar started the building of the monument and it was then later finished by Augustus. After the Basilica had been rebuilt it was dedicated to the grandsons of Augustus: Gaius and Lucius. This monument was a centre of business and a court of justice simultaneously. It was the largest Basilica in the Forum of Rome and was 101 metres by 49 metres in size. The central hall measured 82 metres by 18 metres. The hall consisted of three storeys and the colonnade, two. Within the Basilica Julia the centumviral court were accommodated, 180 magistrates who passed judgement for civil incidents. These magistrates were spread across four chambers. Each chamber consisted of 45 men and each section worked independently. It as only in the case of major and very important trials that the chambers were able to work as a whole unit.
In this floor plan of the forum the Basilica Julia is located on the left and is the long rectangular building. In the plan it has been named 'Basilica Gaii et Lucii'. This is due to it, after reconstruction, being dedicated to Gaius and Lucius.