The cluster of stone structures, now covered by thick vines and accessible only when using a machete to cut through the undergrowth, contain stashes of German coins from the late 1930s, fragments of "Made in Germany" porcelain, and Nazi symbols on the walls.
"We can find no other explanation as to why anyone would build these structures, at such great effort and expense, in a site which at that time was totally inaccessible, away from the local community, with material which is not typical of the regional architecture," said Daniel Schavelzon, leader of the team.
Mr Schavelzon, from the University of Buenos Aires, spent months exploring the site in the Teyu Cuare provincial park, in the Misiones region of northern Argentina.
Thousands of Nazis, Croatian Ustasha fascists and Italian fascists arrived with the blessing of president Juan Peron, who led the nation from 1946 to 1955 and again briefly in the 1970s.
An estimated 5,000 Nazis eventually ended up in Argentina.
In 1960, Nazi Adolf Eichmann, who helped organise the Holocaust, was captured in Buenos Aires by an Israeli commando team and tried in Israel where he was executed.
Josef Mengele, whose grotesque experiments on prisoners at Auschwitz earned him the title "Angel of Death", also fled to Argentina.
"When the war was over some useful Germans helped us build our factories and make the best use of what we had," said Peron, who died in 1974.
North Korean state media has reported the discovery of the lair of a unicorn ridden by an ancient Korean king.