”PACUIUL LUI SOARE” ISLAND In the north-eastern part of the island Păcuiul lui Soare, which splits the Danube waters from the right of Ostrov commune to the front of Dervent hill, are the ruins of a fortress. Of the initial surface, of approximately 5 ha, probably describing a rectangular shape, only part of it remains today, the western part of the fortress being covered by the Danube waters.
The preserved portion of the island fortress is bordered in the south-east by another wall, whose length measures 240m, on a height of 5-6m, with the width between 4.20m and 6m built in the “blockage” system, supported on an oak sub-construction. The outer fortifying elements are the gate, the port installation and towers. The gate, arranged on the northeast side, is a rectangular tower (14.70 x 10.50m), paved with large stone slabs, representing in fact a foundation platform, with one or two floors, with two entrances (one, exterior, cataract type and the second, interior, arranged in the thickness of the enclosure wall, keeping in this area the start of a stone block vault); the access to the floor was made of stone steps built in the curtain at the west door