Bayern had finished fourth in 2006-07 and missed the Champions League. The response was the most aggressive transfer window in the club's history, and Ribéry was its centrepiece at a fee that made German headlines.
He stayed twelve years, won nine league titles, and was named UEFA's best player in Europe for 2012-13. His pass set up Robben's winner at Wembley.
Why it worked: he arrived at 24 with his best football ahead of him, and the club kept extending rather than cashing in.
On the fee
The figure above is a reported fee. Bayern, like most German clubs, do not confirm transfer amounts, so contemporary press reporting is the best available record and add-ons are rarely disclosed. Where a fee is disputed, this site says "reported around" rather than quoting a false precision.