The aisled St. Mary's Church of square ground plan whose lateral walls have been preserved almost to their original height. The size of the church (11x 24 m) indicates a large population of the nearby castrum erecting this edifice in the 5th - 6th centuries.
The altar area is two steps higher and is divided from the church nave by a partly preserved triumphal arch. The altar basis is preserved in situ. The atrium of the basilica holds a small collection of stone monuments, exhibiting, among other, church finds, transennae, stone window grids.
The front part of the basilica and around it was the site of an Early Christian cemetery 300 m long, stretching as far as the southeastern corner of the castrum.
The beginning of the 9th century saw the renovation of numerous churches, among them St. Mary's. It was refurbished with new stone furnishing bearing the recognizable interlace pattern. The large pagan population must have caused missionary activities carried out by the Benedictines from the many monasteries. If not earlier, this is when the Benedictine monastery was founded stretching north and south of the church.
In the 13th century the basilica belonged to the Templars, but when their order was abolished in 1312, life in the monastery faded away.
Near this church, a smaller aisleless church dedicated to St. Peter was built whose floor was decorated by a tricolored mosaic.References:
Trullhalsar is a very well-preserved and restored burial field dating back to the Roman Iron Ages (0-400 AD) and Vendel period (550-800 AD). There are over 340 different kind of graves like round stones (called judgement rings), ship settings, tumuli and a viking-age picture stone (700 AD).
There are 291 graves of this type within the Trullhalsar burial ground, which occurs there in different sizes from two to eight metres in diameter and heights between 20 and 40 centimetres. Some of them still have a rounded stone in the centre as a so-called grave ball, a special feature of Scandinavian graves from the late Iron and Viking Age.
In addition, there is a ship setting, 26 stone circles and 31 menhirs within the burial ground, which measures about 200 x 150 metres. The stone circles, also called judge's rings, have diameters between four and 15 metres. They consist partly of lying boulders and partly of vertically placed stones. About half of them have a central stone in the centre of the circle.
From 1915 to 1916, many of the graves were archaeologically examined and both graves of men and women were found. The women's graves in particular suggest that the deceased were very wealthy during their lifetime. Jewellery and weapons or food were found, and in some graves even bones of lynxes and bears. Since these animals have never been found in the wild on Gotland, it is assumed that the deceased were given the skins of these animals in their graves.