The castle mound is about 30 m high and unusually steep, of elongated form with at dam of 2m height at the northerly part. The place of the ancient town is found to the west of the castle mound. The castle mound was inhabited between the 9th - 13 th centuries. The odds are that the castle mound of Spārni had been castrum Sparnene, the centre of Spārnene lands.
Archaeologically, the castle mound was surveyed in 1960s. Several antiquities were found - wheel made pottery, silver horseshoe-fibula, silver sticks, and a bronze pendant.
