The Portuguese international is the current Fifa World Player of the Year on the back of some breathtaking performances in the Premier League and on the European stage.
Along with Kaka, who Real have already bought for £59m, and Lionel Messi, Ronaldo is one of the three most coveted players on the planet.
He has come a long way from the hate figure of English football, vilified for his part in Wayne Rooney
's sending-off during the 2006 World Cup.
Now, quite simply, Ronaldo is recognised as the best.
So what will Madrid be getting for their money?
He has it all - proficient with either foot, tremendous speed, brilliant dribbling ability, a vicious shot, a free-kick style that he alone has mastered, a goal-poacher's nose, a powerful physique and strength in the air, which was highlighted by heading home the opening goal in last year's Champions League final.
He even manages that little bit of luck all great players seem to have - his penalty miss in the Moscow shoot-out against Chelsea will largely be forgotten as his team-mates got him out of trouble.
Five great Cristiano Ronaldo goals:
1. Manchester United v Porto - An unstoppable shot right into the top corner of the net during a game United had to win.
2. Manchester United v Portsmouth - An absolutely exceptional free kick, hit with pure power and pin-point precision.
3. Manchester United v Aston Villa - A memorable back-heel that pretty much sums up the year he had in 2008.
4. Manchester United v Roma - A magnificent team goal from one end of the pitch to the other that resulted in a clinical finish.
5. Manchester United v Chelsea - A bullet of a header in the Champions League final: the perfect leap, the perfect header and on the perfect stage.