The site of ancient Dion was first identified in modern times by the British colonel and antiquarian W. M. Leake, who visited the region in December 1806 during one of his several journeys through Macedonia. Half a century later, in 1855, and again in 1861 the French archaeologist L. Heuzey visited Dion too. He confirmed Leake’s identification and made additional observations on the visible remains of the ancient city, while he also published some inscriptions.
Excavations at Dion began in May 1928, under the direction of G. Sotiriadis, Professor of Archaeology and Rector of the newly established University of Thessaloniki. During four successive summer campaigns (until 1931) and under adverse conditions, Sotiriadis investigated various areas within and outside the city walls, primarily searching for the sanctuary of Olympian Zeus. Although the main objective was not fulfilled, the excavator identified several buildings, the most significant being a Macedonian tomb with Doric façade and Ionic vestibule and a Christian basilica that had two major building phases. Through persistence and effort, Sotiriadis achieved the construction of a small museum for the safekeeping of the excavation findings as well as of sculptures, inscriptions and architectural members gathered from the surrounding area.
The work was taken up again thirty years later, on the initiative of G. Bakalakis, Professor of Classical Archaeology at the University of Thessaloniki. The focus was once more on the search for the sanctuary of Zeus, yet it produced no results. Moreover, Bakalakis systematically investigated the fortified enclosure. He also located and excavated the Roman theatre outside the city walls and conducted an extensive surface survey. At the same time, Prof. St. Pelekanidis excavated the Christian basilica that had been brought to light by Sotiriadis.
However, the most important period for the excavations at Dion began in 1973, under the direction of Prof. D. Pandermalis. New orientations were followed in the investigation of the city. Particular attention was paid to the search for the sanctuaries and the study of ancient cult, ultimately resulting in the discovery of the sanctuary of Olympian Zeus, as well as those of Demeter, Isis and Zeus Hypsistos, all of them situated in the area outside the south wall. There has also been interest in Early Christian Dion, with further investigations at the site of the intra-mural basilica, which was identified as the Episcopal Church, and the excavation of a cemetery basilica extra muros. Furthermore, the location and uncovering of public buildings, such as the Hellenistic theatre, the Roman Forum and several bath complexes, together with private houses, some being particularly luxurious like the so-called villa of Dionysus, continued. Still, the excavation area included part of the city's extended graveyards.
The excavation work carried out by the Aristotle University of Thessaloniki has continued since that date without interruption. Due to the significant progress that has been made, Dion is considered one of the most important archaeological sites in Greece. Each year a great number of students participate actively in the excavations and are trained in all aspects of archaeological skills. Over the past few years, particular emphasis has been given to the advance of the study and preservation of monuments and artefacts, utilising modern technologies, and to the promotion of the archaeological site.