Geophysical approaches applied in the ancient theatre of Demetriada, Volos Apostolos Sarris*,Nikos Papadopoulos*, Sylviane Déderix*, Maria-Christina Salvi* *Laboratory of Geophysical - Satellite Remote Sensing & Archaeo-environment (GeoSat ReseArch), Institute for Mediterranean Studies (I.M.S), Foundation for Research & Technology, Hellas (F.O.R.T.H.), Nik. Foka 130, Rethymno 74100, Crete, Greece ABSTRACT The city of Demetriada was constructed around 294-292 BC and became a stronghold of the Macedonian navy fleet, whereas in the Roman period it experienced significant growth and blossoming. The ancient theatre of the town was constructed at the same time with the foundation of the city, without being used for 2 centuries (1 st ce. BC - 1 st ce. A.D.) and being completely abandoned after the 4 th ce. A.D., to be used only as a quarry for extraction of building material for Christian basilicas in the area. The theatre was found in 1809 and excavations took place in various years since 1907. Geophysical approaches were exploited recently in an effort to map the subsurface of the surrounding area of the theatre and help the reconstruction works of it. Magnetic gradiometry, Ground Penetrating Radar (GPR) and Electrical Resistivity Tomogrpahy (ERT) techniques were employed for mapping the area of the orchestra and the scene of the theatre, together with the area extending to the south of the theatre. A number of features were recognized by the magnetic techniques including older excavation trenches and the pilar of the stoa of the proscenium. The different occupation phases of the area have been manifested through the employment of tomographic and stratigraphic geophysical techniques like three-dimensional ERT and GPR. Architectural orthogonal structures aligned in a S-N direction have been correlated to the already excavated buildings of the ceramic workshop. The workshop seems to expand in a large section of the area which was probably constructed after the final abandonment of the theatre. Keywords: Geophysical Prospection, Ancient Theatre, Demetriada, Volos 1. INTRODUCTION The city of Demetriada was founded by the Macedonian king Demetrio in 294-292 BC and comprised a large naval station for the Macedonian navy fleet. It was actually flourished during the period when Macedonian kings where the dominant power in Greece and was protected by strong walls indicating its really strategic importance. The city was not a simple another “city ally” but it was rather organized in the prototypes of the Macedonian kingdom cities. Its growth and blossoming has been constant since the mid of 2 nd century B.C. until the Roman period [1]. The ancient theatre of Demetriada was constructed at the same time with the foundation of the city but remained unused for a period of two centuries between 1 st century B.C. and 1 st century A.D due to extensive damages. It is located at the south west side of the modern city of Volos in Thessaly. The theatre was completely abandoned after the 4 th century A.D. with the prevail of Christianism and the modified socio-political transformations that were experienced during that period in the cities. This resulted in using parts of the theatre as construction materials to build new Christian basilica churches. W. Leake was the first to recognize the theatre in 1809. The first systematic excavations were initiated in 1901 by Valerio Stai and continued for two more periods in 1907 and 1912 by Apostolos Arvanitopoulo. The excavation activities by Demetrios Theoxaris (ephoros of Thessaly archaeological service) were actually those that revealed the theatre in late 1950’s (1957-1958; Fig. 1). A smaller excavation project was started again in 1986 that continued with smaller or larger gaps until 2000 [1]. From architectural point of view the theatre exhibits all the basic characteristics of an ancient greek theatre; namely the koilon, the orchestra and the scene (Fig. 1).