The Church dedicated to the Holy Virgo of the Assumption is in a prominent position in the square in the center of Selargius. Ancient documents mention the church since at least 1525, but it was probably built earlier in the XV century to accommodate the growing number of worshippers which were meeting in a smaller church now lost, possibly the near Saint Julian church.
It was initially built with only one central nave barrel vaulted and with a tower bell. It was then enlarged in the XVII century with the addition of six side chapels and the transept. In the same period, the ribbed vault of the presbytery was demolished and replaced with an octagonal dome. After this expansion, the interior layout became a Latin cross plan. In 1664 two sculptors from Cagliari, Pere Ambrogio Cucuru and Juan Baptista Serra, rebuilt the tower bell with stone, inspired by the tower bell of St. James in Cagliari.
In 1771 the barrel vaulted ceiling was renovated with the addition of three-pointed arches with a supporting function. The façade was redone in the XIX century in neo-classical style. The lower part of the façade has a portal with a lunette and two niches at the sides, the upper part has an ogive window. The façade is completed at the top with a triangular pediment. In the same period, the tower bell was replaced with the existing one which conserves an ancient bell fabricated by a Neapolitan ironworker in 1580 and consecrated in 1596.
The interior chapels built in the XVII century are dedicated to different venerations. The chapels at the right of the entrance are dedicated to the Holy Cross, to Madonna d’Itria and Saint Joseph. The chapels at the left to Saint Anthony from Padua, Sacred Heart of Jesus, Madonna of the Rosary. The chapels Madonna d’Itria and Madonna of the Rosary belongs to the respective Confraternities and conserve two wood retables. The church pulpit with polychrome marble is also from the XVII century.
The main altar is dated 1786 and was built with polychrome marbles by Giovanni Battista Franco; the central niche conserves the wooden statue of the Virgo of the Assumption adorned with the estofado d’oro (a special painting technique that resemble precious garments). The statue was sculpted by an artist from the Neapolitan school between the end of 1500s and early 1600s.
The left side of the transept conserves a silver tabernacle decorated with the image of a pelican, symbol of the sacrifice of Christ. At the right side of the transept there is the altar of Saint Lussorio from the XIX century with the statues of the XVI century martyrs Lussorio, Cesello and Camerino which are taken outside in procession to the church of Saint Lussorio the day of the feast of the Saint.
The baptism font with polychrome marble was built in 1729 by the artist Pietro Pozzo from Genoa, hired by Antioco Siddi and Don Pietro de Cervellon as explained in an inscription in Spanish. Above the door of the Sacristy there is a paint of the Dormitio Mariae, the only surviving piece of a XV century retable of Sardinian-spanish workmanship that was decorating the main altar. According to an old document of the priest Felice Putzu, the retable was dismantled and moved to the nearby church of Saint Anthony. An organ built in 1773 and decorated in gold in 1785 is conserved in the choir.
Since 1962 the Church of the Holy Virgo of the Assumption is the main site of the “Matrimonio Selargino”, a remake of the ancient local wedding ceremony. The event combines religious ceremonies with folk and cultural events that bring crowds of locals and tourists.