Walter studied at Gottingen (established in 1734) where he received a doctorate and he worked at the University of Cologne.
Walter studied history, Latin and Greek at Gottingen und Erlangen from 1983. In that year he was appointed as a senior instructor in the faculty of the department of ancient history at the Institute for Ancient World Studies at the University of Cologne. In 1992 he received a doctorate from Gottingen with a work on citizen rights in Archaic Greece. 
