Trajan's Market is the modern name of a complex consisting of buildings and streets arranged on six levels.  The structure was realized to contain the cut executed on the Quirinal Hill in order to gain space for the Forum of Trajan, at the beginning of the second century A.D. Built with a concrete core and a brick facing, the structure is exemplary of Roman engineering. The plan and elevation are designed to adjust to the available space and changes of level.

The arcades in the Trajan Market were considered a shopping mall. Nowadays the compound is considered a multifunctional center, where most of the rooms housed offices or were in relation to the administrative and judicial activities held in the Imperial Fora.

From the forum one can enjoy the view of the semicircular facade of the Great Hemicycle flanked by two half-domed halls.