Nostra Segnora de Mesumundu is located in the archaeological complex with the same name. It was built in the 6th century, during the Byzantine domination of the island, over a pre-existing Roman structure (2nd century AD). The Byzantines re-used part of the walls of the Roman building, as well as the aqueduct. The edifice could have been used as a baptistery. However, it is also possible that it was used for the purification of ill people through an immersion rite.
In 1063, the structure was donated by the Giudice (duke) Barisone I of Torres to the Abbey of Montecassino. When monks came from the Italian religious community, they adapted the building for Roman Catholic use, adding an apse and a new entrance (demolished in 1934). For the work, they used materials from the nearby Roman ruins and the nuraghe Culzu.
References:The Temple of Edfu is one of the best preserved ancient shrines in Egypt. It was built in the Ptolemaic Kingdom between 237 and 57 BC.
Edfu was one of several temples built during the Ptolemaic Kingdom, including the Dendera Temple complex, Esna, the Temple of Kom Ombo, and Philae. Its size reflects the relative prosperity of the time. The present temple initially consisted of a pillared hall, two transverse halls, and a barque sanctuary surrounded by chapels. The building was started during the reign of Ptolemy III Euergetes and completed in 57 BC under Ptolemy XII Auletes. It was built on the site of an earlier, smaller temple also dedicated to Horus, although the previous structure was oriented east–west rather than north–south as in the present site.