The architect Frank Amedeo Pittui narrates and Laurence Gambella translates into English:

"The archaeological complex of "Mesu Mundu" rises up in an alluvial valley surrounded by a series of high basalt plains, a short distance away from the banks of the River Mannu, about km 187 on the SS131 road. In the area, there are numerous springs, among these the so-called "S'abba Uddi" (also termed "Abba de Bagnos") which flows at the constant temperature of 18º C. The presence of the various hot springs has encouraged people to settle in the area from ancient times. For example, the remains of Roman settlements from C3rd AD are to be found near the Roman road "a Turre-Karalis" (from Porto Torres to Cagliari), as well as the more ancient witness of the nuraghe Culzu located on the banks of the River Ruzzu.

Amid the remains of Roman buildings there emerges a small Byzantine temple called St Mary of Bubalis, more commonly known as Our Lady of Mesu Mundu. (...)

Since no documentation exists, the date of the church's construction is uncertain. However, the rediscovery of several tombs, positioned against the walls of the building, supply a terminus ante quem: it must be from C7th or earlier. (...)

An architectural shell remains from the original construction, made up of:
a central body;
a domed rotunda with two large windows with lowered arch open towards the top;
two unequal annexes both with apses, oriented to the west ("A") and to the south ("B"). The first has a barrel vault, the second a wide arched window with semi-dome covering.
On the outside the remains of the northern annexe are visible, consisting in a fragment of wall next to, though no longer fixed to, the rotunda wall. On the east side, the stones are in complete disorder and, consequently, what does remain of the wall cannot be accounted for with great certainty.
At present there are no traces of the original entrance, although it was almost certainly different from the current one, which is notable on the inside for the basalt block, placed there by the Benedictines in CXIth, and on the outside for its brick platband (restoration in 1934).

It is interesting to consider Roberto Caprara's explanation of this: the entrance would have been to the east, in place of the current apse, since the presence of a semicircular construction tallies with there being a rectangular narthex with an apse on both sides. On the outside, immediately to the south of the "C" apse, the foundations of a small niche can be seen, which might ulteriorly confirm the existence of a narthex.

Inside the building, before the latest restoration initiative, the kicking away of the layers of earth on the surface uncovered part of the foundations of the circular hall and as well as other structures, in particular the portion of a rectilinear wall in opus caementicium, made with basalt blocks, and the ruins of the Byzantine water system. This s consisted in a small channel which wound its course round both parts 'A' and 'B' and the hall. Towards the centre the channel is interrupted by a sectioned quadrangular well with a deep hole in the middle, which probably contained the hinge of a small revolving door to regulate the flow of water.

The building recalls Roman style, for its method of construction. The builders built the dome with a concrete mix, positioning it on a circular wall, therefore avoiding the need for a domed vault erected on a quadrangular base.

Part of the structures, as already mentioned, were constructed on existing remains, such as the small, windowed "B" apse built on a stretch of wall in opus testaceum. This was probably an inn or bathhouse while it was a Roman structure, as one can see vaguely on the outside. (...)

In explaining the etymology of the name "Mesumundu", Paulis divides the word in two parts: "Inside it - he observes- we recognise a main part - mesu 'di mezzo', central, what is in the middle' [presumably referring to the presence in the centre of the church of a well in quadrangular form, of uncertain date] and a "mundu" part - mundu [which] is nothing other than memory, handed down to our day by oral tradition and by the waters which once ran where the church was built [...]. This obviously refers to the adjective MUNDUS, "pure, clean, without stain" which especially in Christian circles could be used to designate springs, cisterns, wells [...]. Thus, the church of Mesumundu was built above the remains of a Roman building in which already previously, Christian ideology had encroached, because of the sacrality connected to the healing waters affluent there. The dedication of the temple [...] to the Virgin Mary was probably not, therefore, by chance, since in Byzantine Sardinia [...] the worship of the Mother of God was associated with the miraculous powers of holy water through the rite of the agiasma, a sacred pool dedicated to her. Here the sick bathed hopeful of obtaining a cure».

In any case, the discovery, within the monument, of the Roman age conduit confirms unequivocably the existence of the thermal building, but the possibility that this was already used in the water cult is not, however, to be excluded. (...)

To read the complete italian text of Arch. F.A. Pittui click here