To the Quirinal side of the buildings of Central Body and the Great Hall is a basalt Roman road, which in modern times has been given the name “via delle Torre”.
Currently visible on the road are many works credited to the Severan period (end of the 2nd Century AD).
Going towards Via Quattro Novembre the road hugs the side of the buildings of the Central Body, whilst on the opposite side a series of building raised between the 12th and 17th century along the via della Salita del Grillo are found. They belonged to the Convent of Saint Catherine of Siena.
In this part of the Markets of Trajan the subtle transformation from the Roman to the Medieval is particularly visible. Here was built, in several different phases, a fortification named from the 12th century onwards as the Militiae Tower. Between the 13th and the 15th centuries ownership of the tower passed between important Roman families - the Annibaldi to the Caetani and then Caetani to the Conti with the structure finally being included in the Monastery of Saint. Catherine of Siena in Magnanapoli, which was founded in the 16th century. The complexes subterranean cisterns were in the monastery and they are still visible today next to a working elevator.
In our time the same Milizie Tower characterises the outline of the Market. It is the product of various building works done between the 12th and 13th century. From 1150 to 1200 a palace with a loggia on arches reused the Roman structure. Then between 1200 and 1250 a corner of the loggia was replaced with the high tower made of blocks of tufo, which between 1250 and 1275 was subsequently faced with the bricks that are visible today.