The centre of the early medieval settlement complex in Ostrow Lednicki is concentrated on an island on Lednickie Lake, next to a communication route leading from Gniezno to Poznań. Architectonic relics are located within the range of the second castle and on the foundations of the first one, from the second half of the ninth century. They were raised alongside the south-western fragment of its circumference and are composed of a central chapel which to the west adjoins a rectangular palatium. The chapel was built on a ground plan of a Greek cross with barely distinguished arms which were joined with the eastern apse (a reduced cross octagon) by the circular parts of the wall. A stair well on a circular ground plan adjoins the south-west corner. The chapel lies in the immediate vicinity of an annex later added on, a donjon of sorts (from about the second half of the twelfth century). The palatium includes a multipartition ground floor. Its western part houses a great hall whose vault or dome were supported by two pillars. The walls and foundation were made of stones of erratic origin: gneiss, granite and quartz sandstone, combined with plaster mortar. At present, the extant walls reach a height of at most 3 meters. Archeological and architectonic research conducted inside the rotunda discovered in the south and north arm of the Greek cross two semicircular baptismal receptacles made of plaster, and initially placed in the second half of the tenth century. Work on protecting the ruins has been going on since 1857. In 1950 the first wooden roof was erected but it did not fully safeguard the object. Archeological excavations are being continued. A s teel roof construction, still used today, was installed in the years 1978-1979 but it too is insufficiently effective for safe guarding the ruins from atmospheric factors, not to mention its questionable aesthetic merits. Parallel protection work currently performed intends to combine certain parts with the assistance of cement-lime or cement mortar which tightens the crown of the walls and causes the evaporation of water below the walls as well as progressive corrosion. The basic aim of the results of research and observation presented in the study is to obtain a conception of the revalorization of the ruin. The article, therefore, includes a detailed examination of the building material and an attempt at a relative dating of mortar by analyzing the phase composition. The physical properties of these materials were examined in detail. The causes for the devastation oft he walls were established and laboratory studies on conservation methods were carried out. An analysis of destructive factors and computer research made it feasible to determine the optimal shape and dimensions of a roof which would effectively secure the ruin against the deteriorating impact of atmospheric factors. Work was conducted on a conception of complete revalo rization. In order to make the site more attractive for visitors, it was proposed to create on the inner space of the roof a holographic image which would reconstruct the original architectonic solid. The summary presents the general premises for further conservation work.