Near the village of Bagrėnas, on the left bank of the Nemunas River, stand two historic hillforts. Although little is known about them, the village of Bagrėnas and the former estate, along with the nearby village of Rūdupis, have been mentioned since 1609. These villages were royal, and their peasants enjoyed certain freedoms.
The Žarijai Hillfort is situated on the slope of the Nemunas Valley. It is surrounded by deep ditches to the east and west, a marshy Nemunas Valley to the south, and cultivated fields to the north. The hillfort still features a depression about 20 meters wide, likely a former trench. Behind this, there is an embankment 10 meters high and 35 meters long, made of dark earth and burnt clay. Beyond the embankment,
there is a platform whose southern part slopes gently downwards.
The slopes of the hillfort are steep, reaching up to 32 meters from the side facing the Nemunas River. Due to the dense tree growth and wooded terrain, accessing the hillfort is challenging. Nearby, in an arable field to the northwest of the hillfort, fragments of hand-built, rough, and fired pottery have been found.
To the southeast of the first hillfort lies the second one—Žarijai Hillfort II with a settlement. This hillfort is irregularly shaped, approximately 150 x 280 meters in size, and surrounded by ditches. It features a platform about 15 meters long and 6-7 meters wide. It is said that this site could have housed weapon storages or even a church.