The creation of the Imperial Forums was primarily due to the fact that the Roman Forum, who for centuries was the site of Rome's most important civic activity where business, judicial, civic, or religious activities were conducted, was no longer large enough to sustain the ever growing city and its activities.
In 54 B.C., the first Imperial Forum was built by Julius Caesar and other emperors that followed him added their forums as well.
The first and oldest, Forum of Caesar, was built as a replacement venue to the Roman Forum. The forum included a temple devoted to Venus and a statue of Caesar riding Bucephalus, the celebrated horse of Alexander the Great, was placed in front of the temple.
The Forum of Augustus was built in 42 B.C. and is a commemoration of Augustus's victory in the Battle of Phillippi. After 40 years of construction the temple was completed and inaugurated in 2 B.C. making it the second forum of the Imperial Forums.
The Temple of Peace was built under Emperor Vespasian in 75 A.D. The shape of this square was different than the other two with a row of columns distinguishing the portico from the temple. Also,the central area was not paved like others but instead served as a garden making it similar to an open-air museum with pools and pedestals for statues.Today,this temple no longer exists.
The Forum of Nerva was actually started by Emperor Domitian during his two year reign between 96 and 98 A.D.,but wasn't completed until later when Emperor Nerva took regin givin the forum his name instead of that of Domitian. But it was Domitians idea to build the monumental forum and to unify the previous forums freeing the area that remained between the Temple of Peace the Forum of Caesar and the Forum of Augustus.
The only visible remnants of the Nerva is a wall with two Corinthain columns from the Temple of Minerva, dedicated to the goddess Minerva, the focal point of this forum.
The last and largest of the forums is the Forum of Trajan, once regarded as one of the architectural wonders of the world, which covered an area of 25 acres. It was ordered by the emperor Trajan and designed by the Greek architect Apollodorus of Damascus and built between 107 and 113 A.D. Here one can see remains of the Basilica Ulpia, Trajan's column, the remains of an important library, and other fragments of marble.
The adjoining Trajan's market, built into the Forum, held over a hundred offices and shops.
It was during the dictatorship of Benito Mussolini that orders were given to create the passage of Via dei Fori Imperiali which consisted of digging and cutting through centuries of debris and ruins to do so. Excavations under his fascist regime revealed many archaeological treasures.
This new via linked the Colosseum to the grand 19th-century monuments of Piazza Venezia found next to the Imperial Forums.