The most well-known and researched Viking age grave site of Saarenaa in Piila is located in the middle of the island, in the former Kaarma parish. Archaeological works took place in Piila in two stages: the first excavations were carried out in 1987 (Vello Lõugas) and these were continued ten years later in the years from 1997-to 1998 (Mägi et al 1998). As is characteristic of other Viking age and late-Iron age grave sites of Saaremaa, different types of stone graves were found in Piila as well. This is also common in the neighboring areas of Saaremaa, for example in the west-Estonia, Finland, mid-Sweden, and Gotland.
Among the seven graves uncovered during the excavation works in 1997 and 1998, three different types of stone graves were identified. In 1998, two different trenches were opened. One of these directly adjoined the southern end of last year’s excavations, and the other was done 7 m northwards from the northern border of last year’s trench. This choice was made based on the presumable location of graves. The trenches were made large enough to cover a whole grave with its immediate surroundings. Nevertheless, one more grave was opened and the southern trench was widened for this reason. Both trenches together eventually covered 77 m².
At least three stone circle graves made of large granite stones that were filled with smaller granite stones with 15-20cm diameters and surrounded by cracked limestone slabs as pavement have been discovered in Piila. Cremated burials were found under the filler stones, from the ground level in the middle of the grave. In addition to these three graves, another oval-shaped stonecirclegrave with a 4-4.2 m diameter was excavated that had a 75cm wide hole on its western side that could be interpreted as an entrance. Adjacent to the entrance, potsherds of a Viking Age carinate fine ceramic with a specific decoration was found, but most of the findings (melted bronze items, pieces of artifacts) and cremated pieces of bone (mostly dog bones) were located in the area in the middle of the stone circle grave. Two knives thrust into the layer of filler stones were found as well, but by the ceramics and a belt distributor which was found among other artifacts from the middle area, the grave was dated to be from the 10-11th century.
Right next to it was another similar grave with a 3.8 m diameter. Part of its wall was broken probably due to the foundation of the previously described grave. Even though a pair of scissors was found under the limestone pavement surrounding the grave, the larger part of the artifacts was also in the middle of the grave. By the melted pieces of a chain arrangement, chain holder and probable fragment of bronze bracelet found there, it seems likely that a woman from the 10th or from the beginning of the 11th century was buried in that grave. One other grave with a 3 m diameter had also its wall partly crushed. It held a burial of a male who was buried in the 11th century or in the first part of the 12th century. In the middle of the grave was a 1 m wide charcoal-rich area with plentiful cremated artifacts, like the blade point of a spearhead, fragments of bones, pieces of ceramics, a cross-shaped pendant, and fragments of a penannular brooch. The grave was dated based on the last two.