Santo Tomé el Viejo Church was built outside the walls in the mid-12th century opposite the Gate of El Peso de la Harina (which was opened up in the 16th century when the Gate of El Obispo was closed).
Built in Caleno granite, besides some of its interior elements, it conserves the 12th-century east and south entrances, with their semi-circular arches and archivolts set on columns on the west porch and on the fascia of the capitals to the south; they boast a declaration made up of figurative, plant and geometric motifs. In 1520, the apses were removed from the upper end, together with the arches that separated the naves (replaced by columns forming two large arches on each side) and the layout was reduced to one rectangular nave.
Besides its function as a church, this Romanesque building has had many uses. After the sale of church land ordered by Mendizábal, it became a private building and was used as a garage and petrol station until 1960, when it was acquired by the State. It was designated a National Monument in 1963. It is currently an annex of the Provincial Museum and is used as a storage area for stone archaeological items; it is also open to the general public.
References:The Church of St Donatus name refers to Donatus of Zadar, who began construction on this church in the 9th century and ended it on the northeastern part of the Roman forum. It is the largest Pre-Romanesque building in Croatia.
The beginning of the building of the church was placed to the second half of the 8th century, and it is supposed to have been completed in the 9th century. The Zadar bishop and diplomat Donat (8th and 9th centuries) is credited with the building of the church. He led the representations of the Dalmatian cities to Constantinople and Charles the Great, which is why this church bears slight resemblance to Charlemagne's court chapels, especially the one in Aachen, and also to the Basilica of San Vitale in Ravenna. It belongs to the Pre-Romanesque architectural period.
The circular church, formerly domed, is 27 m high and is characterised by simplicity and technical primitivism.