The Nazi leaders were convicted at Nuremberg trials for war crimes.
They were called the Nuremberg trials. http://www.law.umkc.edu/faculty/projects/ftrials/nuremberg/nuremberg.htm
CHurchill, Roosevelt, Stalin on Allies 22 Convicted
There were several trials, but it sounds as if you are looking for the Nuremberg Trials. Please see the related question.
The Nuremberg Trials were held between November 1945 and October 1946.
Nuremberg is in Germany
The Nuremberg trials were military tribunals conducted by the Allied Forces after the end of WW2. These trials were held for prominent members of Nazi Germany who were accused of war crimes.
The Nuremberg trials were held in Nuremberg, Bavaria, in Germany.
The trials were held in the city of Nuremberg, Germany, from 1945 to 1946, at the Palace of Justice.