The Cathedral, perched on the highest point of the hill, is the city's most emblematic building and home to Tarragona's richest collection of mediaeval art. Construction began on the structure in the mid-12th century, and it was consecrated in 1331 A.D., making it a fine example of the transitional architecture that linked the Romanesque and Gothic periods. The temple has a basilic floor plan with three naves and a stone transept. The 14th century main façade, with its enormous rose window, is of particular interest. On the mullion dividing the massive doors is a beautiful image of the Virgin with the Christ child, in which the prophets and apostles can be seen at the same height. The bell tower has a Romanesque base, but the rest of the structure is done in the Gothic style. The top segment, which is octagonal in shape and studded with soaring windows, houses the cathedral's fifteen bells, some of which date from the 14th century. The high altar has a magnificent frontal from the early 13th century, which depicts scenes from the life and martyrdom of St. Tecla, one of the city's patron saints. The reredos, which was begun in 1429 A.D. and is the work of the sculptor Pere Johan, is of particular interest. Likewise, an arched stone hollow, known as an arcosolium, that stands open on the right wall of the presbytery holds the tomb of the archbishop Joan of Aragon, son of King Jaume II. The sarcophagus evokes the figure of the buried man with great realism and detail. The walls delimiting the choir stalls date from the 14th century and are decorated with mural paintings, while the wooden pews date from the era of Archbishop Pere de Urrea (1445-1489). Among the Gothic chapels, the one known as Capella dels Sastres, or the Chapel of the Tailors, which also dates back to the 14th century, is of especial interest and may well be the complex's finest example of Gothic architecture thanks to its architectural and sculptural ornamentation. Also of note is the baptistery chapel, formerly dedicated to St. Ursula and the eleven thousand virgins and built under Archbishop Arnau Sescomes (1335-1346), with its star vault and intricate detail. The three chapels located at the end of the southern wing are the work of Canon Barceló and date back to the late 15th century. Also worth noting are the chapels of St. Michael and the Presentation in the right nave and those of the Cardona family in the left nave, all done in the Gothic style.

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