From 1971 to 1982 he taught architectural history at the Department of Architecture at the University of Illinois at Urbana-Champaign. From 1982 until his retirement in 2010 he taught as a professor for Early Christian and Byzantine Art at the Department of Art and Archeology at Princeton University. In addition, he was director of the Hellenic Studies Program at Princeton University from 2006 to 2010.[1]
His main area of research was Byzantine architecture, especially the Middle and Late Byzantine Period. In 2010 he presented a summary of his research in the monumental work Architecture in the Balkans from Diocletian to Süleyman the Magnificent.
From 1997 he was a member of the Serbian Academy of Sciences, from 2004 an honorary member of the Christian Archaeological Society in Athens. In 2006 he became a member of the "Experts Committee on the Rehabilitation and Safeguarding of Cultural Heritage in Kosovo" of the UNESCO for the preservation of cultural property in Kosovo.
Publications (selection)
Gračanica. King Milutin's church and its place in Late Byzantine architecture. University Park; London 1979, ISBN0-271-00218-2
Art and Architecture in the Balkans. An Annotated Bibliography. Boston 1984, ISBN0-8161-8326-0