The church dedicated to St. Mary is a basilica from the early Middle Ages and today it is preserved only in its foundations. It is a basilica located on the site of a church in Biskupija, not far from Knin. Franciscan Lujo Marun was the first to conduct research on this church at the end of 19th century and his writings are the basis for any further research. However, Marun's research has left many ambiguities and open questions so Stjepan Gunjača began revisory research of this locality in the 1950s. In addition to the remains of former architecture, many stone fragments of church furniture have been found at the site and it is believed that there are more than a thousand of them. Furthermore, there have been found many graves with rich finds which also helps to date the time of activity of this locality. As the oldest activity we can accentuate the three-nave basilica dedicated to st. Mary, which dates back to the end of the 8th and beginning of the 9th century. Also, the later added western part of the basilica belongs to the time of the oldest architecture and it is believed that the westwerk and the royal mausoleum once stood on that part. Some of the found graves located in the southern part of the basilica and two graves near the northern extension are dated to about that same time. There were several stonemason workshops from different time periods on the site, which suggests that the basilica changed and renewed its inventory several times.