Santuario di Nostra Signora di Bonacattu, Byzantine shrine in Bonarcado, Italy

Santuario di Nostra Signora di Bonacattu is a Byzantine-era church with a Greek-cross plan whose four arms differ in length and are covered by barrel vaults. A hemispherical dome sits inside a square, pyramid-roofed lantern. The western facade, added in 1242–1268, is built of basalt and trachyte with trilobed hanging arches and round niches for ceramic basins.

The sanctuary was erected in the Byzantine era, around the 6th-7th century, over a late-imperial Roman settlement that itself stood on a Nuragic cult site. In 1110 Judge Costantino I de Lacon-Serra of Arborea ceded it to the Camaldolese monks of San Zeno di Pisa, recorded in the condaghe of Santa Maria di Bonarcado; the monks founded a monastery and a larger new church beside it. The western facade in basalt and trachyte was built between 1242 and 1268.

The name Bonacattu, from which the town name Bonarcado derives, is linked to the church's original dedication to the Madonna Panákhrantos, the Immaculate. The main altar holds a 15th-century polychrome terracotta relief of the Madonna and Child, venerated as Nostra Signora di Bonacattu. On 1 January 2016 Archbishop Ignazio Sanna opened the diocese's third holy door here for the Jubilee of Mercy.

The sanctuary stands in the historic centre of Bonarcado, on the small square faced by the apse of the parish church of Santa Maria, so the two buildings are seen together. The interior is a Greek cross with four barrel-vaulted arms of unequal length; the presbytery, in the southern arm, is closed off by a wrought iron railing. The semicircular apse points northeast, and the dome sits inside a square, pyramid-roofed lantern visible from within.

The eastern arm preserves a basin from the original Roman settlement, likely part of thermal baths that served the earlier community. This artifact connects visitors to the deeper layers of the site's past and demonstrates how sacred places often endure across different civilizations.