One of the main forms of expression of the power of the Dacian Kingdom, with its capital at Sarmizegetusa Regia, was represented by the monumental constructions built in ashlar stone, the result of a mixture between local traditions and Greek and Roman influences. The fortified acropolis at Piatra Roșie is one of the main components of this center of power and one of the most important archaeological sites from the Late Iron Age in Romania. In 1999 it was inscribed on the World Heritage List as part of the serial site “Dacian Fortresses in the Orăștie Mountains”. This paper presents the most recent data regarding the stones used in the construction of the Piatra Roșie fortress, the most important building material from the point of view of volume and durability. The historiographical and archaeological data, the field investigations and measurements, together with the mineralogical analysis of stone varieties have been corroborated with specific interpretations for construction engineering and 3D modeling applied in the evaluation of the dimension stone volume. The present approach constitutes an absolute novelty for the site of Piatra Roșie, and, also, a model that can be applied to the specific conditions of the other Dacian Fortresses.

Dacian civilization flourished on the actual territory of Romania during the Late Iron Age and had its peak from the first century BC to the first century AD. They had intensive relations with Hellenistic and Roman civilizations. Therefore, it is difficult to evaluate the origin of some widely spread artifacts discovered in the Dacian archeological sites. The present research is focused on two bronze artifacts (a bronze coin and a mirror fragment) found in the Alun-Piatra Rosie site and a silver coin found in the Ardeu site. Artifacts were investigated with nondestructive methods such as SEM-EDX for microstructural and elemental characterization, and the crystalline phases were investigated using XRD. Bronze coin proves to be an Istrian issue having an elemental composition of 75.0% Cu, 20.8% Sn, and 4.1% Pb, which corresponds to a structure of Cu grains mixed with Cu₅.₆Sn grains. The bronze mirror fragment has an elemental composition of 52.3% Cu and 47.7% Sn, which corresponds to a structure containing grains of Cu₆Sn₅ mixed with grains of Cu₄₁Sn₁₁. It has a smooth surface that was investigated with AFM microscopy, which evidences a Ra roughness of 51 nm for the patina surface and 33.7 nm for the clean metal surface, proving the high quality of the original mirror luster of the artifact. The silver coin was identified as a Radulesti–Hunedoara type meaning that it was produced in local Dacian metallurgic workshops. It has an elemental composition of 63.1% Ag, 25.3% Sn, 7.8% Cu, and small traces of P and Fe, which corresponds to a structure of Ag grains and Ag₃Sn grains. Silver coins show that Dacians uses Sn as alloying element in their metallurgic workshops. Istrian bronze coin proves to be typical for Hellenistic or Roman bronze type with Sn content no more than 25% Sn. The bronze mirror fragment has an unusual composition that might be a result of al local metal charge elaboration with several Hellenistic and Roman bronze pieces as raw material and an extra Sn addition during the melting process. This material facilitates the polishing properties of the active surface that has a very low roughness even after 2000 years of ground resting and adherent oxides patina.