The basilica was a fundamental element of a Roman forum. It was used as a public building, much like the Greek stoa. It also served as a meeting place for administration, as a law court, and as a marketplace. It provided cover and shade for hot or stormy afternoons too After Christianity became the main religion of the Roman Empire, the basilica came to be a church where the masses worshipped, and remains its function today.
In the Forum Romanum of Rome, there were several basilicas constructed throughout the city's history. They were usually named for the person or persons who paid for its construction, and as a way to cement a person's status and recognition throughout Rome.
Basilica Porcia – This building holds the distinction of being the first basilica to be built in Rome. Built by Cato during the period of the Roman Republic in 184 BCE, this was an official meeting place for tribunals (law cases). It was destroyed by fire in 52 BCE and was not rebuilt.
Basilica Aemelia – Of the four Republic-era basilicas constructed in the Forum Romanum, this is the only one to have any substantial remains left today. This large building was erected in 179 BCE by censors M. Aemilius Lepidus and M. Fulvius Nobilior. This public meeting spot was restored between 55 – 34 BCE, when the Tabernae Argentariae (Moneychangers' Shops) were added along the front side (today, the remains of melted copper coins can be seen in the marble floors). What remains is the foundation and some of the columns, following the destruction of the basilica during a sack of Rome in 410 CE by the Visigoths of Alaric.
Basilica Sempronia – This is one of the earliest basilicas built during the Republic in the Forum Romanum, constructed there in 169 BCE. It was built by Tiberius Sempronius Gracchus, a high-ranking Roman and the father of two tribunes, Tiberius and Gaius. Little remains of this basilica, and Julius Caesar had it torn down in order to build his own Basilica Julia in its place.
Basilica Opimia – This late Republic-era basilica was built in 121 BCE by the consul L. Opimius. One of the four original basilicas in the Forum Romanum, it was demolished by Tiberius in order to build a new Temple of Concord. Unfortunately, nothing remains of this building.
Basilica Julia – When Julius Caesar reorganized the Forum Romanum (between 54 – 48 BCE), he had the Basilica Sempronia torn down so that he could construct his own larger and grander basilica. Caesar never saw the completion of the building, and Augustus ensured that it was finished. This large basilica was constructed for official Roman meetings, and it was the home of the Centumviral Court, 180 jurors who heard civil lawsuits. It had to be restored in 9 BCE when a fire severely damaged it, and it was restored again by Emperor Diocletian in 283 CE when another fire damaged it.
Basilica Maxentii (alternatively, the Basilica of Maxentius or the Basilica of Constantine) – This was the last basilica constructed in the Forum Romanum, begun by Emperor Maxentius in 308 CE. It was intended to be the administrative offices for the city's Prefect. It was completed in 312 CE by Constantine, following the defeat of Maxentius at the Battle of the Mulvian Bridge. Constantine altered the original plane of the basilica in order to better suit his own tastes and needs.