The first work on the Forum began in 107 CE. They involved in preparing the right area. For this purpose, it was decided to demolish some tenement houses around the Quirinal Hill. The fate of the tenement houses was also shared by the Atrium Libertatis, which was customary to free slaves. To be able to accommodate the forum of the planned dimensions, a significant part of the hill had to be removed.
The whole square of the forum occupied a space of 300 m by 185 m, however, “proper forum” was a square measuring only 116 m in length and 95 m in width. The Forum floor was paved with colourful marbles. Two sides of the square formed columnar porticoes, behind which extenders 45 m deep, which were the place of many disputes of contemporary intellectuals.
Between the columns of porticos 12 m wide, statues of eminent statesmen were placed. The portico was covered with a roof and had two floors. The upper floor was occupied by an attic, preceded by statues of Dacian prisoners of war.
In the centre of the square was a large, gilded statue of Trajan on a horse. At the opposite end of the Forum, it adjoined Basilica Ulpia), which somehow closed the Forum.
Right behind the basilica, the courtyard stretched 24 m wide and 16 m deep. Two libraries adjoined it on both sides. One of them contained Latin works and the other Greek. The library walls were double and made of brick, which prevented the accumulation of moisture. In the Latin library, in addition to monuments of fiction, imperial, praetorian and other sources of law were also kept. In the middle of the courtyard was a Trajan’s column.
In 117 CE, the Senate resolved to raise an arch dedicated to Trajan at the Forum. On each side, it was decorated with three columns that divided it into five parts. The central part was the entrance. The remaining four parts housed niches in which statues of Dacian prisoners were placed. At the top of the arch was a statue of Trajan in a triumphal cart pulled by six horses.
The ceremonial opening of the Forum was on May 18, 113 CE.
Behind the courtyard was a semicircular square where Emperor Hadrian built the temple of the divine Trajan. It was a monumental building. It is worth mentioning that the facade of the temple consisted of eight columns with a diameter of 2 m each and a height of 20 m. The side ports rose on columns with a diameter of 1, 80 m. The temple was surrounded by a rounded colonnade.