During the MoDeCo2000 scientific and research project on mortars used in the territory of the Roman Danube Limes in Serbia, the biggest challenge was the quest for the provenance of raw materials. The area where Viminacium, the largest city in the province of Moesia Superior developed, with millennial continuity of land use and settlement, was selected as research case study and is presented in this research. People throughout history have always used what they had at hand, and the building remains were not only reused but also recycled for new constructions. Thus, the building material of Roman Viminacium has survived in the landscape through the in situ preserved remains of Roman buildings, as well as in the structures from the later periods, up to today. To the best of our knowledge, the use of natural sediments baked during the self-combustion or combustion of underneath layers (coal in our case) for the purpose of construction was extremely rare in the Roman Empire. In this study, we follow the presence of this type of material precisely in Viminacium construction, naming it natural brick, while focusing on its potential use in lime mortars whose production was perfected in the Roman period and has never been surpassed afterward. Archaeological contexts in which this material was found have been studied, along with simultaneous work in the laboratory and in the field during the research and experimental use of the natural brick in lime mortars. We sought to determine whether this material could have been recognised by Romans in Viminacium as a potential valuable pozzolanic component of mortar, along with or instead of fired brick, being locally available and recyclable. The final confirmation of its pozzolanic features and later discussion open completely new directions for the future research of Viminacium lime mortars.

The main focus of this research was the bio-stimulated healing of cracks in lime mortar samples (historical and newly designed). The investigation started from comprehensive characterisation of historical mortars, while in the next stage a compatible conservation mortar was designed and characterised, with special attention given to the contact zone formation between original and conservation mortars. The next step was the design of a bio-stimulating crack-sealing agent, a two-component liquid system: bacteria culture Sporosarcina pasteurii DSM 33 and nutrients. Both historical and conservation mortar samples were used in order to study their potentials for bio-stimulated surface-crack repair. The experiment lasted for 150 days, allowing the ureolytic bacteria Sporosarcina pasteurii DSM 33 to induce the precipitation of calcium carbonate into cracks and heal the damaged surface of the tested materials. The healing phenomenon was continuously monitored during a period of 150 days. Special attention was given to the evaluation of the morphology, chemical and structural characteristics of the deposits created in/on the surface cracks, monitored by optical microscopy, SEM, XRF and XRD analyses. The obtained results present valuable input for the application of the developed system in real environmental conditions as a solution for the future sustainable architectural conservation of traditionally prepared mortars.

Viminacium was the capital of the Roman province of Moesia Superior and an important legionary fortress. Today it is an archaeological park with protected and presented historic buildings and contemporary facilities, situated by the thermo power plant and strip coal mine near Kostolac in Serbia, and it is identified as a cultural property of exceptional importance for the Republic of Serbia. The protection and presentation of the historic buildings in Viminacium to date can be divided into groups as follows: basic protection and presentation; integrated protection and presentation through interpretation; and integrated protection and presentation through reconstruction and revitalisation. All the processes can be discussed within the framework of the evergreen topic of heritage conservation - the quest for the proper protection and presentation of buildings, which is often connected with the spatial context.

The tomb G-160, known as the 'Tomb with Cupids', was discovered in 2003, during the excavations at the Pirivoj - Viminacium necropolis. The tomb has a trapezial section, characteristic for Viminacium tombs of the late antique period, and its interior was painted using the fresco technique. Scenes and motives are set on all four walls of the tomb. Since the western wall is damaged, the tomb is named after the depiction of cupids on the eastern wall. The wealth of the iconographic repertoire, together with an analysis of the geometry and symmetry, allowed the reconstruction of the conceptual context and it can be concluded that the tomb was dedicated to Venus, or Dionysus. The tomb painting could be dated to the beginning of the 4th century, owing to the analysis of the style, which combines an eclectic Eastern expressionism, classicism and illusionism of the Constantine era.