Layers of Rome: A Summary of the History of the Forum of Caesar

Oct 2023
10-minute read

The Layers of Rome project is currently working toward developing a virtual walking tour of the Old and Imperial fora of Rome. Our ultimate goal is to make Roman history more accessible to the general public, as it is immensely difficult to make sense of a field of ruined structures without prior reading. It is our hope that the Layers of Rome map will be able to bridge the divide between site and context with a brief summation about chosen sites accompanied by reconstructed images of the sites as they stood in antiquity. As it is intended to be used on-site, while visitors stand amidst the ruins in the (at times oppressive) Italian heat, the map’s site descriptions have been limited to 300 words. What follows is a collection of all the research and context behind those 300 words for the Forum of Caesar.

Rear of Temple of Venus Genetrix and Forum of Caesar by Josh Munoz   

In digging through the layers of Rome, one will find that the storied history of a site such as the Forum of Caesar is, on closer inspection, fragmentary, hopelessly entangled, and in some cases, outright contradictory. These results have not been unexpected. Such uncertainty has, in my experience, been part-and-parcel of dealing with ancient sources, and the forum itself has not survived the ravages of time well. What follows is a description of what has thus far been pieced together concerning the chronology of the aforementioned Forum of Caesar.

The Forum Iulium, colloquially referred to as the Forum of Caesar, was the first of the imperial fora. Built at the behest of Julius Caesar, it was initially planned as a simple project of expansion and renovation. However, the project would be reshaped by its tumultuous historical environment, going through numerous additions and alterations until it stood as a monument to one man and his family, designed to overshadow the old Forum Romanum and the republic itself.

Rome: Forum Iulium: Plan. ded. 46 B.C. Image from

By 54 BC, the prosperity and growth of the empire was significantly outpacing the aged infrastructure of the city of Rome, and the ancient Forum Romanum was in desperate need of expansion, particularly in regard to space for state business. It is known that the proposition was being tossed around amongst the highest levels of society, as such a public service would bring great prestige to its patron.

Caesar, while still embroiled in his decade-long conquest of Gaul(1), seized the initiative and had Cicero purchase land for the project on his behalf at great expense. It is possible that Caesar desired to construct a space to rival the colossal theater complex built by Gnaeus Pompeus “Pompey” Magnus, his one-time ally turned rival, in the Campus Martius.

It is presumed that construction began in 51 BC, but construction was likely halted when civil war between Caesar, his allies, and the Senate broke out in 48 BC. On the eve of the civil war’s penultimate battle at Pharsalus in August 48, Caesar vowed a temple to the patron goddess of his gens (a group of families who share a name and common origin; clan), Venus Genitrix, in exchange for victory over Pompey and the Senate. Caesar carried the day.

It is speculated that Caesar would have had to purchase more land to accommodate the temple to Venus Genitrix in the plan of the forum, which he personally dedicated during his great triumph of 46 BC. With his final victory in the civil war in 45 BC, Caesar may have wished to consolidate his influence over state affairs and make what was originally intended to be only an extension of the Forum Romanum into a separate forum entirely – a node of Caesarian power in the heart of the city bearing his name.

Evidence of this shift in purpose can be inferred from the construction of Caesar’s Senate House, the Curia Julia. The Curia Hostilia, the ancient senate house of Rome, had been burned to the ground in a funeral riot (the funeral of Publius Clodius Pulcher is worthy of its own article) in 52 BC and replaced by the much larger and more prominently sited Curia Cornelia in 51 BC. Caesar had the Curia Cornelia converted to a temple and made preparations to replace it with the Curia Julia in 44 BC, set further back and directly connected to his now functionally separate forum. Why would Caesar move to decommission what was essentially a brand-new senate house that was larger than both the Curia Hostilia and his Curia Julia? It is noted that the Curia Cornelia was unpopular, but it is also possible, if not probable, that Caesar seized on the Curia Cornelia’s disfavor to exert greater influence over the Senate while also diminishing its dominant position in the Roman state. Caesar would not live to see his forum completed. At a meeting of the Senate in the Theater of Pompey on March 15, 44 BC, he was betrayed and murdered by a treacherous, conniving cabal of senators, many of whom the man had called his friends.

Completion of the forum would fall to Octavian, who was not only Caesar’s grandnephew, but also his adopted son and the future Augustus. The forum would finally be completed in 29 BC with Augustus having expanded the piazza southward and the building of the Curia Julia concluded.

The forum was of a rectangular design, 377 ft. long and 100 ft. wide, with columnated porticoed aisles bordering the open piazza at the west, east, and south ends, framing the temple of Venus Genitrix. The forum was formally separated from the Forum Romanum by a peripteral enclosure wall(2). The western portico housed a host of senatorial offices, archives, and storage for functions of the temple and state.

The temple was of a Corinthian order peripteral octastyle(3) design with its rear wall embedded into the ridge connecting the Quirinal and Capitoline hills (which will be important later). Its podium featured a speaker’s platform, making it ideal for holding public assemblies, the bedrock of Caesar’s Populares faction. The cella(4) housed the cult statue of Venus Genitrix sculpted by the renowned Greek sculptor Arcesilaus.

Rome: Forum Iulium. ded. 46 B.C. Image from

It is known that an unusual equestrian statue of Caesar, featuring a horse with human feet, stood in the center of the forum. Pliny the Elder also attests that the forum was home to a sizeable collection of fine Greek art and spoils of war (including a gilded statue of Cleopatra commissioned by Caesar), serving as something akin to a public museum.

There is evidence that the forum was renovated several times by successive emperors. A colossal statue of Tiberius was erected near the temple in 30 AD by 14 cities of Asia Minor(5) that had received earthquake relief. 

Major changes occurred between 95 and 113 AD. It is possible that the forum was damaged by a fire that ravaged the city under the reign of Emperor Titus in 80 AD. Evidence suggests that Emperor Domitian undertook a complete rebuilding of the forum and Curia Julia in 94-95 AD, cutting back the ridge that comprised the rear wall of the forum and Temple of Venus Genitrix. The entirety of the ridge was eventually quarried away to facilitate the construction of the Forum of Trajan. This would have necessitated a program of total reconstruction of the temple. With Domitian’s assassination in 96 AD, construction halted. Being subject to Damnatio Memoriae, damnation of his memory, any attribution to or records of Domitian’s involvement with the rebuilding program would have been destroyed by Senatorial decree. This work of Domitian was only uncovered by more recent analysis of the decorative schemes of the temple’s entablature, revealing a distinctly Flavian(6) style. What was left incomplete upon Domitian’s death sat dormant throughout the reign of Nerva until Emperor Trajan finally completed the work, rededicating the Temple of Venus Genitrix in 113 AD. It is primarily the remains of this Domitianic and Trajanic rebuilding and enlargement of the temple that are visible today.

Trajan also constructed the addition of the Basilica Argentaria(7) to the southern end of the western portico, which connected the Forum of Caesar with the Forum of Trajan. Trajan is also credited with the addition of a second story to the porticos complete with public latrines.

The forum was again devastated by fire in 283 AD, leading to a final program of restoration and reconstruction by Emperor Diocletian. The Curia Julia was completely rebuilt in 303 in its current iteration. Diocletian also despoiled the original white marble columns of the porticos and substituted them for the smaller multi-colored columns that remain today. A wall was also constructed cutting across the northern end of the forum, closing off the colonnade along the facade of the temple, leaving only a single central entrance and large arches on either side of the podium as passageways. The southern portico was also walled in and had rows of pillars removed, creating a large antechamber to the Curia Julia, possibly serving as storage for the censorial archives.

From at least 390 AD, the forum was home to the Secretarium Senatus, responsible for criminal trials against members of the Senate.

Early Christian designs found in the pavement of the Basilica Argentaria suggest that part of the structure may have been converted into a small chapel, perhaps that of San Abacuc. This conversion may coincide with the decree of Emperor Theodosius in 392, outlawing the practice of paganism throughout the empire, which would have seen the Temple of Venus Genitrix shuttered.

The fall of the western Roman Empire in the 5th century and the turmoil that followed was not kind to the Forum of Caesar. The collapse of the city’s population saw habitation contract to the areas of the Campus Martius and Trastevere, leaving the imperial fora largely abandoned. The forum, its temple, and porticoes were scoured and dismantled over subsequent centuries for their valuable marbles and basic building materials. Pope Honorius I converted the Curia Julia into the Church of St. Adrian in 630, thus preserving the structure. Pope Honorius also had the church of Santa Martina built over the site of the Secretarium Senatus in 625, around which the Academy of Saint Luke was constructed (demolished in 1930s).

Imperial Forums--Caesar's Forum  Forum Iulium  Forum Julium  Forum Caesaris (Image from Jstor). Built by order of Julius Caesar, and reconstructed by Emperor Domitian. Imperial Forums--Caesar’s Forum / Forum Iulium / Forum Julium / Forum Caesaris. Construction began in 54 BC and completed in 46 BC; forum destroyed by fire in 80 AD; total reconstruction in 95 AD under Domitian.

The area of the former Forum of Caesar became steadily built up, first host to small farmsteads in the 9th and 10th centuries, and eventually coming to resemble something much like the surrounding neighborhoods still present, as the city began to prosper once again. These neighborhoods would subsequently be demolished to facilitate the excavations of 1930-33, revealing all that is presently visible of the forum today.

The purpose of the Layers of Rome walking tour is to give visitors a quick glimpse into the vast history of each site in front of which they may spend only minutes or moments. However, it is our hope that this interaction with the archaeological sites in conjunction with our synopses will prompt a desire to learn more about each site’s grander and much more lengthy and complex history.


1.  Roughly modern France

2.  An outer wall enclosing the whole Forum of Caesar, separating it from the Old Roman Forum.

3.  An eight-columned façade with free-standing columns surrounding the sanctuary.

4.  Sanctuary of the temple housing the cult statue.

5.  Corresponding roughly to the Anatolian peninsula.

6.  The Flavian Dynasty: Emperors Vespasian, Titus and Domitian, ruling from 69-96 AD.

7.  Basilica meaning a Roman hall or lawcourt rather than the ecclesial definition.


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