The mother church of Guardia Lombardi is the Church of Santa Maria delle Grazie (), which was established in the year 1315. Its first architectural design was cruciform, specifically in the shape of a Greek cross. This building was destroyed by an earthquake on 5 December 1456 and was rebuilt upon the initiative of the feudal lord of Guardia, Maria Donata Del Balzo. In 1665, a bell tower was added to the edifice. With the Irpinia earthquake of 1980, the church was once again destroyed. It was later rebuilt and restored. It was reopened in 1999 as it now stands today, within the territorial jurisdiction of the Archdiocese of Sant'Angelo dei Lombardi-Conza-Nusco-Bisaccia.