Ask anyone what is wrong with modern day football and the most common answer will be money. Not only the huge wages that players receive but also the phenomenal transfer fees that some players move for.

With the summer transfer window rapidly approaching, it is widely expected that there will be a number of new additions onto this list of the most expensive transfers ever.

Many player's transfer fees can sometimes be higher depending on certain novelties. For example, within England, young players with huge potential are rare enough to attract significant fees that far outweigh the player's true value.

So with that in mind, here's a look at the success (and failures) of the 15 most expensive transfers in football history.

15. Pavel Nedved

From: Lazio

To: Juventus

Fee: £30.7 million

Year: 2001

Inflation Adjusted Fee: £38 million

Success: To fill the boots of Zinedine Zidane is never going to be easy for anyone, but the Czech legend Pavel Nedved gave it his best shot, and proved that he was a wise purchase by the Turin club.

He won a number of Serie A titles with the club and helped the team to the 2003 Champions League Final against AC Milan.

14. Dimitar Berbatov

From: Tottenham Hotspur

To: Manchester United

Fee: £30.75 million

Year: 2008

Inflation Adjusted Fee: £31 million

Success: A late transfer in the 2008 Summer transfer window, Dimitar Berbatov took a little time to settle in at Manchester United. Ever after he had, there was little shown that put him ahead of any of the club's other strikers.

In the 2010-2011 season though, Berbatov finally hit his stride and he currently stands as the leading scorer in the Premier League, making the high fee worthwhile.

13. Andriy Shevchenko

From: AC Milan

To: Chelsea

Fee: £30.8 million

Year: 2006

Inflation Adjusted Fee: £33 million

Success: Arguably one of the biggest transfer flops of recent times, Andriy Shevchenko was a Champions League winning striker, who had been regularly competing for the Ballon d'Or at AC Milan.

After joining Chelsea, he scored a few goals here and there but never looked the same player again. Eventually he returned to his old club Dynamo Kyiv as a disappointment in the Premier League.

12 Christian Vieri

From: Lazio

To: Inter Milan

Fee: £32 million

Year: 1999

Inflation Adjusted Fee: £41 milllion

Success: For such a significant fee, it was always going to be hard for Christian Vieri to prove his value was that high at Inter, although he did a good job of coming close.

He won the Supercoppa Italiana and Coppa Italia with the club and hit 103 goals in 143 appearances, making him a very valuable player during his six years at the club.

11. Robinho

From: Real Madrid

To: Manchester City

Fee: £32.5 million

Year: 2008

Inflation Adjusted Fee: £33 million

Success: Robinho had his moments of magic at Manchester City, but the general consensus amongst most fans is that he was a bit of a flop for the Premier League rich boys.

Just six months into his injury plagued second season at the club, Robinho moved away on loan back to Santos, before securing a permanent move away to Milan that summer.

10. Gianluigi Buffon

From: Parma

To: Juventus

Fee: £32.6 million

Year: 2001

Inflation Adjusted Fee: £40 million

Success: It's always difficult for goalkeeper's when they're valued so highly, as they have so much pressure resting on their shoulders during a game.

If anyone could cope with that though, it has been Gianluigi Buffon, who has been a rock at the back for Juventus through thick and thin for 10 years, making him a very successful purchase.

9. David Villa

From: Valencia

To: Barcelona

Fee: £34.2 million

Year: 2010

Inflation Adjusted Fee: £34.2 million

Success: He's only been at Barcelona for just under one season, but it's evident already that David Villa was quite a smart buy for the club.

Villa has been a regular starter for a Barcelona side that many have called the best the world has ever seen, scoring over at a rate of over 0.5 goals per game for the Catalan giants.

8. Andy Carroll

From: Newcastle United

To: Liverpool

Fee: £35 million

Year: 2011

Inflation Adjusted Fee: £35 million

Success: It was widely known that even at the time of the transfer, £35 million was a shockingly big fee for such an unproven player.

His potential is very high, and his few performances since coming back from injury have also been positive, but it seems very unlikely that he will prove to be worth the amount paid for him.

7. Hernan Crespo

From: Parma

To: Lazio

Fee: £35.5 million

Year: 2000

Inflation Adjusted Fee: £45 million

Success: Personally, Hernan Crespo's stint with Lazio was successful, with him scoring most of the club's goals in all competitions and being on fine form throughout his two years at the club.

However, his only trophy with the team was the Supercoppa Italiana, and after hitting injury in his second season, he eventually moved on to Inter Milan two years after signing for Lazio.

6. Luis Figo

From: Barcelona

To: Real Madrid

Fee: £37 million

Year: 2000

Inflation Adjusted Fee: £46 million

Success: Quite possibly the most controversial transfer on this list, Figo moved between the two major Spanish rivals for a record fee in 2000.

Figo had a successful time in Madrid however, as a key part of the famous Galactico's era in which he won two La Liga titles, one Champions League, two Supercopa de Espana titles, one UEFA Super Cup and one Intercontinental cup.

5. Zinedine Zidane

From: Juventus

To: Real Madrid

Fee: £45.7 million

Year: 2001

Inflation Adjusted Fee: £55 million

Success: Like Figo, Zidane was signed as part of the Galactico's era at Real Madrid and helped form one of the fiercest midfields the world has seen.

The famous French midfielder had some of the best years of his career at Real Madrid winning numerous trophies and adding to his already strong legacy as one of the finest French midfielders in history.

4. Fernando Torres

From: Liverpool

To: Chelsea

Fee: £50 million

Year: 2011

Inflation Adjusted Fee: £50 million

Success: It's hard to judge as Torres has only been at Chelsea since the end of January, but from performances so far, fans have dubbed him the £50 million statue.

When he's on top form, Torres is known as one of the best strikers in the world, but so far he has done very little to back that up, and he could prove to be one of the most expensive transfer flops in history.

3. Kaka

From: AC Milan

To: Real Madrid

Fee: £55 million

Year: 2009

Inflation Adjusted Fee: £56 million

Success: Signed by Real Madrid in an attempt to reignite a second Galactico's era, Kaka was expected to be a huge boost to Real Madrid.

It's no secret that his best years were at AC Milan, and while Kaka may have put some strong performances in for Madrid, it's hard to see where the valuation of £55 million came from.

2. Zlatan Ibrahimovic

From: Inter Milan

To: Barcelona

Fee: £56.5 million

Year: 2009

Inflation Adjusted Fee: £57 million

Success: Maybe one to rival Fernando Torres transfer to Chelsea, Ibrahimovic was not quite as successful at Barcelona as people would have hoped for.

While still contracted to the club officially, he is now on loan at Milan, where he has found his best form again. He might well have another chance to prove himself in Barcelona, but in all likelihood he'll be offloaded permanently in the summer.

1. Cristiano Ronaldo

From: Manchester United

To: Real Madrid

Fee: £80 million

Year: 2009

Inflation Adjusted Fee: £81 million

Success: The biggest transfer fee in the history of football, regardless of talent and performances, transfer fees quite so high can never truly be justified.

Ronaldo has very much picked up at Madrid where he left off with Manchester United, in fact creating an even better scoring record for himself in Spain. A lack of trophies can only come down to Barcelona's dominance in Spanish football, but regardless of his top form, Ronaldo should never have been worth the huge £80 million paid for him.