This article presents an analysis of the spatial structure and the chronological development of Opstainis, Vilkyškiai Iron-Age hill-fort settlement, on the basis of archaeological and geomagnetic survey data. It has been ascertained that the hill-fort and the settlement were inhabited throughout the first millennium AD. The currently available scientific research data from Opstainis, Vilkyškiai Iron-Age hill-fort and settlement (half-sunken building or pit houses, oval-shaped and pear-shaped flatbottom household pits, and shards of handmade pottery decorated with cross-shaped imprint ornaments) serve as indications of contacts between the inhabitants of the lower reaches of the River Nemunas and the southwest Baltic Sea region in the second half of the first millennium AD.