Exterior

The western tripartite façade features two pilasters that divide the three sections vertically and frame the central part that is higher than the two lateral ones. The outer façade reflects the inner division of the church aisles. The top rim of the church is closed by a string of hanging arches sitting on shelves with plant motifs. The main portal with lintel stands in the central section of the façade, and is framed by two marble columns with Corinthian capitals that support a projecting cornice. The statues of the patron saints Nicholas and Sabinus sit on the cornice, in alignment with the columns. At the centre of the composition, a niche houses the statue of St. Mary of the Assumption.

The two smaller portals on the side sections correspond to the inner aisles, and are framed by two columns with Corinthian capitals that support a broken arch tympanum. The openings on the façade are distributed symmetrically. A smaller rose window (oculus) is located in the upper part of the prospectus just below the triangular cusp. A richly decorated rosary-bead frame defines the upper half of the large rose window, and supports a series of animal and plant sculptures (acroteria). The internal radial pattern dates back to the 1930s restoration that replaced the previous Baroque-style mixtilinear aperture.

The northern prospectus is punctuated by a series of deep blind arches surmounted by an arcade composed of sets of elegant hexafora, which are six-light mullioned openings, divided by piers, and consisting of rounded arches on columns with bell-shaped capitals. The prospectus is visually interrupted by a massive cylindrical structure that abuts the church called the Trulla. It was the baptistery up to the 17th century, but then, the archbishop Ascanio Gesualdo transformed it into the sacristy. Beyond the Trulla, it is possible to catch a glimpse of the northern front of the transept. In the base section, it is possible to discern three large blind arches whose recesses contain further combined blind arches in which small quadrangular windows, framed by perforated stone slabs, open up at the top. These outer wall surface features are typical of Romanesque architecture, and, although they do not have a specific structural function, they make the walls appear lighter. In the upper section, there are two stages of two-light mullioned windows. Further up, under the outthrusts of the cusp, there is a rose window with a richly decorated rosary-bead motif frame in the middle.

Two tall bell towers once flanked either side of the compact eastern prospectus. The south-facing left tower came tumbling down during an earthquake in the 1600s and was never rebuilt, while the north-facing right tower was completely rebuilt in the years 1948-50. The lower stage replicates the blind arch motif described in the northern prospectus. It is interrupted in the middle by a large apse window that is characterized by a rich frame with spiral plant motifs, and two shelves on which two column-bearing elephants support, on their backs, octagonal columns with figured capitals. Two mythical creatures above the capitals, a sphinx, on the right, and a griffin, on the left, form the base for a deep protruding arch with an ornately carved intrados (inner curve of the arch). The eastern prospectus presents apses embedded inside the masonry. This feature of the Cathedral of St. Sabinus stylistically resembles that of the Basilica of St. Nicholas where the apses are hidden, thereby conferring to the building a massive and compact appearance. This technique was used for the Cathedral in Bari, and the ones in Bitonto and Giovinazzo, but not for the cathedral in Trani.

The cathedral perimeter closes with the southern prospectus that is identical to the northern one. It also has large deep blind arches and a hexafora arcade (six-light mullioned round-arch openings) that was completely rebuilt during the restoration of the early 1900s. On the side of the transept, it is worthy to note the four animal-shaped shelves with column-bearing bases of the 13th century that protrude on either side of the lower stage bifora (two-light mullioned windows).

Interior

The tripartite division of the western façade reflects the interior three-nave floor plan. The inscribed transept is slightly out of alignment with respect to the longitudinal axis of the naves, perhaps due to urban constraints or pre-existing structures. Three apses at the end of the eastern side of the church align with the naves. Sixteen columns, eight per side, separate the central nave from the two lateral aisles. Corinthian stucco capitals, which were rebuilt in Romanesque style during the 1930s refurbishment, cap the columns. They support large double wheel arches surmounted by triple mullioned windows of the faux matronea (internal galleries intended for women).

The single-light mullioned windows of the clerestory above the galleries allow light into the nave. Below the triple-light mullioned windows of the women's galleries, there are visible traces of the shelves that supported the walkways running along the upper inner perimeter of the Cathedral. A perforated stone balustrade encloses steps that lead to the chancel through a large triumphal arch. The dome is positioned above the chancel and sits on a sixteen-sided drum that, in turn, is mediated by an octagon with four hemispherical pendentives.

The 13th-century ciborium, by Alfano from Termoli, stands in the centre of the presbytery atop of three steps, and frames the altar. It was demolished in the 18th century, and then completely rebuilt by Schettini who retained some of its original features. The ambo (raised oblong pulpit) is situated between the sixth and seventh column on the right. It, too, was reconstructed reusing and repurposing original parts.

The crypt

The crypt is located beneath the transept, and, like the rest of the cathedral, was refurbished in Baroque style in 1738 under Archbishop Muzio Gaeta according to designs by the architect Domenico Antonio Vaccaro. It is the only remaining evidence of the 18th-century phase that survived the radical depredations that the building suffered at the beginning of the 1900s when its medieval image was allegedly restored. The crypt is divided into thirty-six square bays, with cross vaults, defined by twenty-four columns arranged in three rows. The columns are clad in Baroque marble facings. The two minor apses display fragmented frescoes of the 14th and 15th centuries. There are currently three altars. The high altar is dedicated to St. Sabinus, and, it is worthy to note the festoon around the grating, the wildly perforated step, and the elegant stylistic white marble features, comparable only to the altars of the Church of San Giacomo (St. James).

The Succorpo

The vast hypogeum church underneath the Cathedral is called the Succorpo. A small door located at the top of the flight of stairs on the right that leads down to the crypt provides access to it. The space consists of several rooms, and extends underneath the entire surface of the church above, and, in some points, even beyond the cathedral’s outer perimeter. The underground halls were re-opened to visitors in 2009. Walking through these halls is like travelling back in time, as far back as to the ancient Roman city. Archaeological excavations and refurbishments have provided a much clearer understanding of the stratigraphy of the structure, and a chronological ordering of the historical events that evolved in this area. Four main historical phases can be identified: 1) Roman and Late Antiquity Phase (1st-4th century). Two parallel walls belong to this phase. They consist of large limestone blocks that delimit a 22-meter by 3-meter space, slightly out of alignment with the orientation of the current church above the underground area. Two smaller walls, two basins, a fragment of a geometric-patterned polychromatic mosaic flooring composed of limestone, tiles, pebbles and clay fragments, and a short stretch of a paved road have been ascribed to this phase. 2) Late Antiquity and Early Middle Age phase (5th/6th to 11th century). There is the presence of an early basilica constituted by a large 7-metre long central nave with apse, and two smaller 4-metre long aisles. The church incorporates a burial ground consisting of four limestone box tombs. The western section is partly cut away by the current facade foundation wall of the cathedral above. Here, it is possible to admire an ornate mosaic pavement in the centre of which lies a large circle surrounded by a double intertwined ribbon that encloses a central square bearing a mat-like motif. Four smaller squares branch out of the corners of the central square, and, between these, there lie circular rings. A wavy orange ribbon interweaves the smaller squares and the rings. The mosaic pavement surrounding the large central disc features pelta-like motifs (crescent-shields) made with light-coloured tesserae contoured by a line of orange tesserae. The Latin inscription is an important element for the history of both the cathedral and the entire city itself. The inscription mentions a bishop named Andrea, and Timothy, the man who commissioned and financed the artwork in order to fulfil a vow. Marine animals and floral motifs adorn a band that runs the length of the three sides of the floor. Geometric motifs and intersecting circles decorate the northern side of the hall. Towards the eastern side, there are fragments of octagonal mosaics connected by squares. 3) Medieval Period (1034 – 15th century). The outer walls and the piers of the Succorpo, which make up the largest hall with cross vaults and serve as the foundation of the upper church, are ascribed to this period. 4) Modern and Contemporary Age (16th – 20th century). This is the period in which the underground spaces were predisposed for the creation of a burial ground.