Trajan's Forum was the last of the Imperial fora to be constructed in ancient Rome. It was built on the order of the emperor Trajan with the spoils of war from the conquest of Dacia, which ended in 106. The Forum was inaugurated in 112, while Trajan's Column was erected and then inaugurated in 113.
The Forum consisted of a vast portico-lined piazza measuring 300 metres long and 185 metres wide exedrae on two sides. The main entrance to the forum lay on the southern side, via a triumphal arch surmounted by a statue of Trajan in a six-horse chariot. The Basilica Ulpia lies at the north end of the piazza, which was cobbled with rectangular blocks of white marble and decorated by a large equestrian statue of Trajan. On either side of the piazza are markets, also housed by the exedrae.
North of the Basilica was a smaller piazza, with a temple dedicated to the deified Trajan on the far north side facing inwards. The position of - and very existence of - the temple dedicated to the deified Trajan is a matter of hotly contested debate among archaeologists, particularly clear in the ongoing debate between James E. Packer and Roberto Meneghini. Directly north of the Basilica Ulpia on either side of the forum were two libraries, one housing Latin documents and the other Greek documents. Between the libraries stood the 38-metre Trajan's Column.
In the mid-9th century, the marble cobble blocks of the piazza were systematically taken for re-use, because of the good quality of the lime. At the same time, the pavement was restored in wrought as a sign that the piazza was still in use as a public space.
In modern times only a section of the markets and the column of Trajan remain. A number of columns which historically formed the Basilica Ulpia remained on site, and have been re-erected. Today Trajan's forum has become well known for its large population of feral cats.References:
The Arch of Constantine is situated between the Colosseum and the Palatine Hill. It was erected by the Roman Senate to commemorate Constantine I's victory over Maxentius at the Battle of Milvian Bridge in 312. Dedicated in 315, it is the largest Roman triumphal arch. The arch spans the Via triumphalis, the way taken by the emperors when they entered the city in triumph.
Though dedicated to Constantine, much of the decorative material incorporated earlier work from the time of the emperors Trajan (98-117), Hadrian (117-138) and Marcus Aurelius (161-180), and is thus a collage. The last of the existing triumphal arches in Rome, it is also the only one to make extensive use of spolia, reusing several major reliefs from 2nd century imperial monuments, which give a striking and famous stylistic contrast to the sculpture newly created for the arch.
The arch is 21 m high, 25.9 m wide and 7.4 m deep. Above the archways is placed the attic, composed of brickwork reveted (faced) with marble. A staircase within the arch is entered from a door at some height from the ground, on the west side, facing the Palatine Hill. The general design with a main part structured by detached columns and an attic with the main inscription above is modelled after the example of the Arch of Septimius Severus on the Roman Forum.