The Diocesan Museum of Tarragona, which is entered through the Cathedral cloister, consists of four rooms, which were most recently refurbished in 2014. These four areas offer a chronological journey from Roman times to the 18th century. The origins of the collection can be traced back to the mid-19th century, although the actual museum was founded in 1914 by Bishop Antolín López Peláez with a collection of liturgical objects from the Cathedral Chapter, the parish churches of the diocese, religious congregations and private individuals. Over time the collection has grown to include some 10,000 items.

The museum has liturgical objects from the 6th and 7th centuries and carvings from the 12th and 13th centuries. However, its most outstanding collection is from the Gothic period (14th and 15th centuries), especially the paintings, carvings and gold and silverwork, including some by well known, internationally influenced artists such as Bernat Martorell, Jaume Ferrer II and Lluís Borrassà. From the Renaissance the museum has exhibits by local artists, while from the Baroque period (17th and 18th centuries) of particular note are the works of Lluís and Francesc Bonifàs i Massó.