Mylonas was awarded his second Ph.D. by Johns Hopkins in 1928; his dissertation was published as the first volume in the series presenting the results of the Olynthus excavations. In the same year, he took a temporary teaching job at the
University of Chicago, which allowed him to remain in the US until 1930. On his return to Greece, he directed the excavations of the
Mycenaean site of Aghios Kosmas in
Attica. The project, under the auspices of the Archaeological Service, began in 1930 and continued in 1931. He also made a study of the
topography of Attica and taught part-time at the Ioannis Metaxas
gymnasium, a high school. From 1930, he excavated at
Eleusis alongside the Greek archaeologist , who tasked him with uncovering the Bronze Age remains towards the southwestern part of the site and with excavating under the building considered to have been the
Telesterion, the focal point of the
Eleusinian Mysteries. Mylonas was at Olynthus with Robinson for the 1931 excavation season, having been sent by the ASCSA in response to the school's dissatisfaction with Robinson's excavation methods. Mylonas returned to the United States later in 1931: he was hired by
William Abbott Oldfather, the dean of the
University of Illinois at Urbana-Champaign, as a temporary assistant professor on an annual salary of $2,200 (). Mylonas excavated at Olynthus in 1932 and 1933, and at Eleusis each year from 1932 until 1934. at Mycenae, excavated by Mylonas and Papadimitriou in 1952–1953 In 1933, Mylonas was hired on a permanent basis at
Washington University in St. Louis as an assistant professor in the Department of Art History and Archaeology. Robinson had previously tried to maneuver another of his students, James Walter Graham, into the position. Mylonas wrote to Robinson, crediting him with securing him the position through his influence and contacts. Mylonas became a
naturalized US citizen in 1937, though spent most of his time in Greece. By 1938, he had been promoted to full professor. He served on the ASCSA's managing committee between 1937 and 1939, returned to Olynthus as co-director of the excavation with Robinson in March–June 1938, and made exploratory excavations at
Mekyberna – the port of Olynthus –
Polystylos and
Aspropotamos, all in
Greek Macedonia, in the same year. Mylonas became chair of Washington University's Department of Art History and Archaeology in 1939. He returned briefly to the University of Illinois for the 1939–1940 academic year, before resuming his post in St. Louis. During
World War II, he orchestrated the founding of the
Greek War Relief Association, a charity which raised money to alleviate poverty in Greece. He also delivered lessons to officers of the United States Army on the Eastern Mediterranean, and wrote
An Introduction to the History of the Balkan States, which aimed to make a historical case against the legitimacy of the
annexation of Greek Macedonia by Bulgaria and was published in 1946. He returned to the ASCSA's managing committee in the same year. The Greek government suspended all archaeological investigation in the country after the war, a state of affairs which continued until 1952. Mylonas spent the 1951–1952 academic year on a
Fulbright scholarship, teaching at the National and Kapodistrian University of Athens (as the University of Athens had been renamed). Simultaneously, he served as an annual professor at the ASCSA; following the suggestion of the chairman, Charles Morgan, that a vice-chairman be appointed in case he was called for military service, Mylonas was given the position. Mylonas also led the school's 1951–1952 "Summer Session" for visiting archaeology students. Once the Greek ban on excavation was lifted, Mylonas entered what Vogeikoff-Brogan calls "an excavation frenzy". He worked at
Pylos under Blegen, where he cleared a
Mycenaean chamber tomb in the nearby cemetery at
Volimidia; he also worked at Aghios Kosmas, and at Eleusis in the same season. On December 22, 1951, he visited, along with John Papadimitriou, what would become known as
Grave Circle B at Mycenae, which had been discovered that November by the
ephor Seraphim Charitonidis during restoration of the nearby
Tomb of Clytemnestra. Mylonas and Papadimitriou cleared the area of the grave circle between January 5 and 11 the following year, funded by Washington University. Papadimitriou was appointed to lead the excavation, and himself organized a committee of archaeologists, consisting of Mylonas, Charitonidis,
Antonios Keramopoulos and
Spyridon Marinatos, to oversee the work. The first season of excavation began on July 3 and continued until October 10, by which point seven tombs had been fully uncovered. That September, Mylonas also directed a return excavation of the underwater shipwreck first discovered at
Artemision in 1926. He co-directed the second season at Grave Circle B, which ran from July 31 to the first third of October 1953, with Papadimitriou; in this season, a further eleven tombs were excavated. The two returned to co-direct the third and final season of excavation, which Mylonas considered the most productive, between July 8 and September 6, 1954: this time, six more tombs were uncovered, leaving the central area of the grave circle fully excavated, and remains of
Middle Helladic buildings in the eastern area of the site were investigated.", discovered by Mylonas in 1954, showing the blinding of
PolyphemusBetween 1952 and 1957, Mylonas co-directed the excavations at Eleusis with
John Travlos: in 1954, his work in the Western Cemetery uncovered the
Eleusis Amphora, considered among the finest examples of
proto-Attic art. From 1957 until 1985, he led excavations on the citadel of Mycenae. He re-excavated most of the acropolis of the site: Tsountas had cleared it in the late nineteenth century, but died before publishing the results of his work. Much of Mylonas's work on the acropolis concerned the establishment of a chronological sequence for its various constructions, particularly the
palace and the fortifications surrounding it; he traced the initial fortification of the site to the fourteenth century BCE, with further development throughout the thirteenth century BCE. He excavated areas of settlement to the north and west of the citadel, including (between 1962 and 1964) a section which he named the "House M Quarter". He also investigated the site's
Cult Center, to which he gave its modern name on the grounds of his interpretation of the structure as a focus for religious ritual. Mylonas held a Fulbright Professorship at Athens in 1954, and spent periods throughout the 1950s at the
Institute for Advanced Study in
Princeton, New Jersey. His
M.A. students in the late 1950s included the Anglo-American archaeologist
Elizabeth Schofield, later known for her work at
Knossos, at
Lefkandi and on the island of
Kea. He served as president of the
Archaeological Institute of America between 1957 and 1960, becoming the first foreign-born person to hold the post, and held a visiting professorship at the ASCSA in 1963–1964, during which he conducted a tour of Crete and offered a course in Mycenaean civilization. In 1964, he stepped down as department chair at Washington University; he was made the inaugural Rosa May Distinguished Professor in the Humanities in 1965. == Return to Greece and later life ==