The sober front features a façade of squared ashlar in calcareous stone, ending in two layers which protrude above a horizontal cornice running across the whole exterior. There are only a few elements which interrupt this seamless appearance: four steps precede the portal which is marked by a double cornice with architraves and an upper rounded fanlight. This has two wooden shutters composed of twenty four identical, geometrical tiles. Above, aligned with the portal, is a large, Baroque window of mixtilinear form, set next to four blocked-up, single-lancet windows. Additional refurbishment and restoration work is visible on the façade, in particular on the section above the large Baroque window and the central part of the gable. On the lateral exterior on Via San Giacomo, there is a door with lunette window depicting the saint in relief, as well as the upper windows which allow light into the church.

The bell tower is incorporated from floor to ceiling within the brickwork of the presbytery and stands rotated slightly away from the direction of the building.

The simplicity of the façade is in stark contrast to the late Baroque appearance of the interior, designed by the Campanian architect Antonio Vaccaro between 1745 and 1747. The church, based on a single space measuring 24 x 11.65 metres, is covered by a barrel-vaulted ceiling with fanlights. Richly decorative stucco extends throughout the walls of the church. In particular, the decoration framing the arch of the apsidal conch and the large window above are characterised by two expansive, symmetrical spirals. The pilaster strips, attached to columns which divide the ten chapels along the side walls, support a trabeation surmounted by wooden jalousie windows which concealed the nuns attending services in the women’s gallery. The chapels have a reduced width, sufficient to hold six marble altars within the three central aisles. The inner surfaces of the chapels’ rounded arches are decorated with stuccoes which underline the window shutters and keystones with rosettes and shells.

The apse contains the principal, 18th century altar in multi-coloured marble, with a bas-relief of San Giacomo framed by palm leaves in white marble. This work of art, together with the six lateral altars, was carried out by C. Tucci. A lattice-wrought golden skylight with Baroque frieze is set in the absidal conch. The 18th century silver tabernacle door shows bas-reliefs portraying the holy trinity and the Medici saints. Above the altars there are paintings which show Madonna with child between San Rocco and San Giacomo, Santa Francesca Romana, the Blessed Bernardo dè Tolomei, San Benedetto in Glory, Sant’Anna and Maria as Child and the Adoration of the Shepherds. A picture of the Immacolata del Reggio hangs above the main altar.

The 17th century floor is composed of glazed terracotta tiles in yellow, white and green which depict large spiral motifs. The two multi-coloured marble fonts are also noteworthy. Created by Tucci from Vaccaro’s drawings, they show the Holy Ghost in the form of a dove.