45 Archaeology and Science 18 (2022) Bjelić - Use of building materials during the...(45-58) INTRODUCTION Te remains of Trajan’s Bridge are located in the riverbed and on the banks of the Danube river, where, on the lef side of the river they are in the territory of today’s Romania, and on the right side in the territory of the Republic of Serbia (Fig. 1). In Romania, they are today part of the urban fab- ric of the city of Drobeta – Turnu Severin, while on the Serbian side they are located 5 km from the small town of Kladovo, that is, 1.3 km east of the nearest settlement, Kostol. On the initiative of Emperor Trajan, the bridge was designed by the architect Apollodorus, be- tween 103 and 105, that is, between two Roman conquest campaigns in Dacia. On two occasions - in 1931 and in 1968, D. Tudor synthesised early knowledge about the remains on the Romanian side (starting with the 1858 research conducted by Deustler, Imbrišević and Popovici and the 1907 re- search conducted by Duppereux)(Tudor 1974: 47). At the same time, he presented his analysis and new views on the architecture of the bridge. Te remains of the bridge were investigated on the Serbian side in 1979 and soon afer they were published by its researchers Milutin Garašanin and Miloje Vasić on behalf of the Institute of Archaeology in Belgrade (Fig. 1) (Гарашанин и Васић 1980). More recently, C. Crăciun and A. Sion, and I. Bjelić have carried out further analyses based on all previous research (Crăciun and Sion 2006; Bjelić 2020). Regarding the construction of the bridge, we can diferentiate two parts: One part was on the shore and, according to the relief on Trajan’s Col- IGOR BJELIĆ Institute of Archaeology Belgrade, Serbia E-mail: igor_bjelic@yahoo.com Received: October 11 th 2022 Accepted: November 15th 2022 Original research article UDC: 904:624.6"01"(282.243.7.043) https://doi.org/10.18485/arhe_apn.2022.18.4 USE OF BUILDING MATERIALS DURING THE CONSTRUCTION OF TRAJAN’S BRIDGE ON THE DANUBE ABSTRACT Combining diferent building materials was not uncommon in Roman architecture. Te use of various materials for the creation of the Trajan’s Bridge on the former Danube Limes, that is wood, stone, brick and mortar, according to their characteristics, role in the construction, chosen construction methods, and pre- known behaviour of these materials over time, is one of the important features of the design of this building. Te reasons for a deeper analysis of architect Apollodorus’ solutions for the bridge regarding the achieved combinations of materials are the importance of the structure, the monumentality of its architecture, as well as the characteristics of the place where the bridge was built. Te focus of this study will be on analyses of the bridge’s masonry structures and, more precisely, the relationships between the building materials used for their construction. When studying the use of building materials, ancient writings were used, as well as analyses of the remains of the bridge in situ on the Danube banks of today’s Serbia and Romania. Te real- ised analyses point to new interpretations regarding the possible ways to span the spaces between the pillars on the riverbanks, and their connection to the choice of building materials. KEYWORDS: BUILDING MATERIALS, CONSTRUCTION METHODS, MASONRY STRUCTURES, TRAJAN‘S BRIDGE, ROMAN ARCHITECTURE, DANUBE LIMES.