The square assumed its current structure in the second half of the eighteenth century, with the intervention of the architect Luigi Vanvitelli; the "Foro Carolino" commissioned by him was to constitute a monument celebrating the sovereign Carlo III di Borbone.
The works lasted from 1757 to 1765, and the result was a large hemicycle, tangential to the Aragonese walls, which seen horizontally incorporated Port'Alba to the west, and flanked the church of San Michele to the east.
From 1843 the central niche constitutes the entrance to the Jesuit boarding school, which became in 1861 “Convitto Nazionale Vittorio Emanuele II”, housed in the rooms of the ancient convent of San Sebastiano and of which the two cloisters are still visible (the dome of the church collapsed in May 1941); the smallest and oldest is a rare example of Naples between the Romanesque and Gothic periods, the largest preserving the sixteenth-century structures.
On the opposite side of the hemicycle the respective ex-convents are situated in addition to the churches of Santa Maria di Caravaggio and San Domenico Soriano: the first became the seat of the institute for the visually impaired founded by Domenico Martuscelli (remembered with his bust carved in 1922 by Luigi De Luca is located in the gardens of the square) and then became the seat of the Second Municipality of Naples.
In September 2011, the square was completely inhibited from private traffic to discourage the use of cars in the city, becoming a fast lane for the exclusive use of public transport.