About 4 km to the east of the ancient Tarsatica, on the Solin Hill above Martinšćica and the Draga Valley (Draška dolina) in the municipality of Kostrena, a Late Roman fortlet of the same name is located. Its position at 240 m above sea level gave it a good view of the surroundings, especially the land and sea routes to Tarsatica.
The top of the hill, where the Solin fortlet is located, was inhabited already in the Stone Age. On the north side, it is protected with natural precipitous walls and on the more easily accessible south side facing the sea, a barrier wall was built during the Late Roman times, which partly followed the route of the prehistoric drywall and was well adapted to the terrain.
The wall was 2 m wide and had 3 quadrilateral towers. All the towers are located centrally on the axis of the wall and have entrances on the inner, northern side. The middle tower is also passable, as it has a narrow passage for one person also on the outer eastern side, just next to the wall. By the western double tower – such towers can also be found on the Ad Pirum fort and the Gradina above Pasjak fortlet – there is a main entrance to the Solin fortlet with a preserved stone threshold.
Archaeological research of the Solin fortlet has been taking place since 2007. Up until today, the major part of the barrier wall in the length of 120 m and three towers have been researched and conserved. The western part of the wall, which was damaged during the Second World War, was more poorly preserved. Soldiers dug up their positions along the inner part of the wall and this part was also bombarded in the final battles of 1945.