 He also frequented other major centres of Orthodoxy such as Jerusalem and Mount Athos.In 1966 he was ordained to the priesthood within the Ecumenical Patriarchate and was tonsured as a monk, receiving the name "Kállistos".In 1966, Ware became Spalding Lecturer at the University of Oxford in Eastern Orthodox studies, a position he held for 35 years until his retirement.