Among the honours he has won were: Second place in the 1955 Mediterranean Games, four times Balkan Games winner and three times winner in the Pan-Hellenic Games.
His greatest honour however came in the 1956 Melbourne Olympic Games: On November 26, after an epic 8-hour battle, Roubanis won a bronze medal in the pole vault, with a jump of 4.50m , setting a Greek record - which would not be broken until 8 years later - and ending a drought of 44 years in which Greece had not won a single medal in athletics.
In order to attend the Melbourne event, Roubanis lost a semester of his studies at UCLA, U.S.A. He abandoned athletics in 1961. After studying political economics, he got his master's degree in local self-government. He had worked in the USA for 5 years as a management consultant for a movie company. He had also set up an advertising company and a printing plant. In sports, he served as the President of the Panhellenic Association of Calisthenics and founded several other associations.