The Tottenham striker joined Inter from Coventry in 2000, having burst onto the English football scene with Wolves and then the Sky Blues.
His time in Milan did not go entirely as he had planned, with first-team opportunities proving hard to come by.
He did, however, embrace the time he spent in a different football culture and insists he would do it all again given half a chance.
"I was only a young lad at the time but it's something I will never regret," Keane told Sky Sports News.
"I had a great time over there, I really enjoyed it. They are great people over there so it's something I can look back on, to go over there as a 19-year-old kid and play for one of the biggest clubs in the world, as one of the greatest times in my life and something I will never forget."
It is easy to see why Keane found it so difficult to get a game at Inter around that time, with their squad laden with world-class attacking talent.
Keane added: "(Christian) Vieri, Ronaldo, (Alvaro) Recoba were all there. They were great players and playing with good players every day in training, you obviously learn a lot and I think it really helped me as a player."
The current Inter squad is equally as talented, and they are the current holders of the Champions League crown.
Spurs will need to be at their best then in midweek if they are to take anything off the Serie A giants, but Keane is confident Harry Redknapp's men can compete on a level playing field.
He said: "You have to be. If you look at the squad of players we have now, there is no reason why we shouldn't go there and be confident enough to get a result."
Keane is also hoping that he will be given an opportunity to impress against his former employers, having found himself restricted to the substitute's bench for much of the current campaign.
"It would be nice," he said.
"It would be a great game to be involved in. Hopefully I will play some part and it would be nice to score and help us to get a good result."