## 1 Introduction  
Public baths played an important role in Roman culture and life. A remarkable expression of Roman hydraulic engineering, the use of public baths started to spread towards the end of the third century BC throughout the Roman Empire. Functioning as spaces of great social significance, public baths developed in time into more elaborate complexes (_thermac_), frequently luxuriously decorated [1, 2, 3]. A variety of information exists on the imperial public baths, especially regarding the ones in the Italian Peninsula, while the bathing facilities found in the provinces have started to be studied only more recently [4]. According to the current state of research, within the Roman province of Dacia, almost 40 small baths have been discovered until now, located within the forts (_praetorium_) as well as in the civilian settlements (_extra munros_) [4]. Compared to other baths found in Moesia Superior, the ones in Dacia (a frontier province), are, in most cases, modest and relatively early structures built between the second century and first half of the third century. Monumental bath structures, which can be associated with an elite residence, are just the ones found at Apulum and at Ulpia Traiana Sarmizegetusa [4; 5]. In this paper, several wall painting fragments discovered in the Roman baths from the archeological site Alburnus Maior (Rosia Montana, Romania) [5] were investigated with the help of an array of non- and micro-invasive analytical techniques. Dated from the beginning of the second century AD, these rare findings stand among the oldest examples of preserved decorative polychrome paintings on plaster excavated thus far in the former territory of the Roman province of Dacia. Due to the small number of scientific studies carried out thus far on Roman mural paintings coming from this region [6], this study is considered important as it can offer valuable information not only in terms of materials and painting technique but also in terms of archeological insights. Roman wall paintings have been intensively studied as early as the nineteenth century, particularly wall painting supports and pigments coming from Rome and Pompeii [7]. Wall painting fragments discovered in other parts of the empire such as Northern Italy, Spain, France, Great Britain, Greece, and Slovenia have also been investigated [8; 9]. However, within the province of Dacia, mural decorations have been significantly less studied. This situation can be explained by the fact that in this area, such findings are scarce. Unlike Gaul or Britain (where the Roman wall painting technique was an established tradition developed in workshops), in Dacia, the existing mural paintings were created by craftsmen that were brought from other provinces for specific commissions only [10]. Moreover, the recovery and study of wall paint evidence is also a matter of survival, excavation technique/skill, and, not least, environmental factors which may help natural preservation or not. In the province of Dacia, there are very few examples of preserved Roman paintings, with isolated discoveries often grouped around monumental buildings [10; 11; 12]. To this date, there has been only one scientific study published on second century Roman wall painting fragments discovered at the archaeological site of Ulpia Traiana Sarmizegetusa, the findings being associated with the decorations of a _domains_[6]. A few other papers mention discoveries of Roman mural paintings at Ulpia Traiana [12], Porolissum [13], and Apulum [10; 11], but these are mainly archeological studies. The lack of scientific investigations concerning Roman painted plasters coming from other archeological sites located in the former province of Dacia made us consider new wall painting fragments for analytical investigations--in this case, murals discovered at the Alburnus Maior archaeological site.