The ruins of the church of St. Dionysios are still visible on a flat terrace just below the summit of the Areopagus in Athens, overlooking the Athenian Agora. Early travelers noted the church often in their writings from the 17th and 18th centuries but opinions were divided on the date of its construction. Investigations by the American School of Classical Studies at Athens in 1934 revealed an Archbishop's Palace next to the church and a cemetery dating as far back os the 7th century A.D. but further excavations in 1963 proved conclusively that the current church could only be dated as far back as the 16th century. This booklet, an offprint from the journal Hesperia (Volume 34: 3, pp. 157 to 202), presents the evidence from the excavations, as well as arguing that, even if the current building is quite recent, there was an ecclesiastical building on this site from a much earlier period; perhaps even from soon after St. Paul's speech to the Council of the Areopagus in 51 A.D.