The Portugal international quit Manchester United in 2009 for an £80m move to the Bernabeu.
Ronaldo, 32, had an impressive spell in England, winning three Premier League titles during his time at Old Trafford under Sir Alex Ferguson.
The forward has become arguably the best player in the world since joining Real, winning four Ballon d’Or’s and becoming the club’s all-time leading goalscorer.
And Ronaldo says he felt he had to leave United for Real for a fresh challenge in the Spanish capital.
“When I became a Manchester player, it was a moment of maximum pride for me. But I think it was more for my family,” Ronaldo told The Players’ Tribune.
“At the beginning, winning trophies was very exciting for me.
“I remember when I won my first Champions with Manchester, the emotions surpassed me.
“I had always admired Madrid and wanted a new challenge”
“Same with the first Golden Ball. But my dreams were getting bigger.
“I guess that’s how dreams work, right?
“I had always admired Madrid and wanted a new challenge.
“I wanted to win trophies with Madrid, break all the records and become a legend of the club.”