The greatest football teams of all time are discussed in almost mythical terms, with the names of their stars being passed from generation to generation.
While Liverpool supporters to this day grow up hearing of the exploits of Kenny Dalglish and Kevin Keegan, the same applies the world over. At Santos in Brazil, for instance, Pele's hold on the identity of the club remains strong to this day.
There will no doubt be great sides that have not made this list, it is not supposed to be comprehensive. The Busby Babes, Cruyff's Barcelona and Eusebio's Benfica are among those not included.
However, our 15 great teams of the past come from 14 different clubs, and an array of countries from both Europe and South America.
So,let's take a look at some of football's greatest sides and the stars who made them so special.
The famed La Maquina side of River Plate in the 1940s was an almost unstoppable force in Argentine football in the 1940s, winning four titles in the space of six years between 1941 and 1947.
Built around a famed five-man forward line of Juan Carlos Munoz, Jose Manuel Moreno, Adolfo Pedernera, Angel Labruna and Felix Loustau, River Plate were one of the most aesthetically pleasing sides of their time.
Between the three most revered of the attacking unit—Moreno, Pedernera and Labruna—they contributed nearly 600 goals to the River cause. Labruna, single-handedly, would score almost 300 times for the Buenos Aires giants.
Often described as playing an early version of "total football," River's W-M formation was known for its incredibly fluidity and movement in attack. They were a side truly ahead of their time.
Jose Manuel Moreno, Adolfo Pedernera and Angel Labruna.
The Real Madrid side of the late 1950s won a remarkable five consecutive European Cups, writing their name in football history indelibly.
While the tournament was only in its formative years, the Santiago Bernabeu-funded side were beating every challenger placed before them.
Their fifth title, played in Glasgow in 1960, would go down as one of the greatest games in history. Real beat Germany's Eintracht Frankfurt 7-5 on the evening, in front of a crowd of well over 100,000 at Hamden Park.
The capture of Argentine icon Alfredo Di Stefano, supposedly aided by the intervention of General Francisco Franco, was the side's big capture. However, Hungarian hot-shot Ferenc Puskas and Brazilian Didi, for one season, were among the other big names to head to Spain.
Spanish captain and central midfielder Jose Maria Zerraga, too, played an important role in the middle of the pitch for Los Merengues, but it was the foreign players and Spanish inside-left Francisco Gento who were the real stars of the show.
Francisco Gento, Alfredo Di Stefano and Ferenc Puskas.
When it comes to the great sides of world football, Uruguay's Penarol continually find themselves overlooked—despite their great history of success and famous players.
Between 1958 and 1962, the Montevideo side won five consecutive national championships, two Libertadores titles and an Intercontinental Cup, in 1961.
They were finally displaced from the top of the South American game in 1962 by Santos, in a game that saw Pele come head-to-head with Ecuadorian great Alberto Spencer.
Spencer was Penarol's star, scoring over 300 times for the club in his 500 appearances. He is still renowned as one of the greatest headers of a ball to this day.
Alongside him played Juan Joya, a tricky Peruvian left winger with a one-in-two goalscoring rate for the club. The duo, along with Uruguayan forward Jose Sasia, would be the team's main threats.
In 1961, against Eusebio's Benfica, the trio would score a combined seven goals over three games to secure the Intercontinental Cup.
The club would win the title once more in 1966, securing their place among the world's greatest sides.
Juan Joya, Jose Sasia and Alberto Spencer.
The Santos side of the 1962 and 1963 seasons is fondly remembered as one of the very best in South American football history, and it is seen as the defining period of legendary striker Pele's career at club level.
The side won back-to-back Libertadores titles and Intercontinental Cups, beating Benfica and AC Milan in the process.
Goalkeeper Gilmar is one of the greatest Brazilian players of all time, and perhaps the best Brazilian goalkeeper ever, while defensive midfielder Zito was also a twice World Champion with Brazil in 1958 and 1962.
One of the most recognisable faces on the planet, No. 10 Pele needs no introduction and was key to the side's setup and success.
Beyond those three, fellow forwards Pepe and Coutinho also rank among some of the best players of their era.
Pele, Zito and Gilmar.
The Botafogo side of the 1950s and 1960s was without doubt one of the best footballing outfits ever seen, even if they could not match Pele's Santos on a continental level.
Three Torneio Rio-Sao Paulo wins between 1962 and 1966 placed the side right at the top of the Brazilian game, and they had star quality few other sides can claim to match.
While the likes of ground-breaking full-back Nilton Santos, left winger Mario Zagallo and much-respected central midfielder Didi were ageing by this point, they were still performing at the very highest level domestically.
Add the mercurial talents of Garrincha into the mix from the right flank, and it is easy to see quite how they were so successful.
By 1966, and the last of the three titles, the team had successfully evolved to incorporate several of Brazil's next generation.
Among those, right-sided forward Jairzinho and central midfielder Gerson would go on to play important roles for Brazil at the 1970 World Cup.
Garrincha, Jairzinho and Nilton Santos.
The "Grande Inter" side of the 1960s, coached by Helenio Herrera, is famed for its great success over a number of years, as well as its refining of the catenaccio system.
Herrera created a team that won games through their impenetrable defence, knowing that they had enough quality in attacking areas to get themselves on the scoresheet.
The dynamics of the system, which has its supporters and critics, can be seen in an excellent tactical breakdown here.
Spanish international Luis Suarez was brought with Herrera from Barcelona to play as the pivotal figure in midfield, while the roles of Giacinto Facchetti and Jair on the flanks were also crucial.
Sandro Mazzola, the team's inside-right, and Mario Corso, on the left-wing, were the main goalscorers.
It may not have been the most attractive football to watch, but it was certainly highly effective.
Luis Suarez, Giacinto Facchetti and Sandro Mazzola.
Coming off the back of three consecutive Bundesliga titles, it is fair to say that Bayern were already a more than useful side. Between 1974 and 1976, though, they would go on to win the first three of the club's four European titles.
In 1976, to complete the club's domination, they would also add the Intercontinental Cup to their cabinet with defeat of a Cruzeiro side now featuring Jairzinho.
The names of Franz Beckenbauer, Gerd Muller, Uli Hoeness and Karl-Heinz Rummenigge have all become part of footballing folklore, while Paul Breitner would also play a part in the team's rise before a move to Real Madrid.
It was a team that swept through all before them, with strength from back to front that went unrivalled across Europe. Lauded sweeper Beckenbauer and record-breaking goalscorer Muller, in particular, were the envy of a continent.
It would take until 2001 for the Bavarian giants to once more conquer Europe—an indication of the magnitude of the period in the club's history.
Franz Beckenbauer, Gerd Muller and Karl-Heinz Rummenigge.
Following Liverpool's rise to the top of the English game under Bill Shankly, the next challenge was to transfer that success onto the continental stage—which they did under Shankly's assistant, and successor, Bob Paisley.
In Paisley's nine-year spell at the helm at Anfield, the club would win a remarkable six league titles, three European Cups and one UEFA Cup. It was a period of unprecedented success for English football.
The names of the players are still fresh in the memory of those who watch English football. From Emlyn Hughes to Alan Hansen and Steve Heighway to Alan Kennedy, Liverpool had big names right across the pitch. Many are still public figures to this day.
Among that group, though, are the team's former stars. "King" Kenny Dalglish, who only recently managed the side once more, football manager and pundit Kevin Keegan, and steely midfielder-turned-pundit Graeme Souness.
Paisley's team evolved between his three European Cup wins, developing on from the good work of Shankly. When one star, such as Keegan, departed, though, they were quickly replaced by another.
Kenny Dalglish, Kevin Keegan and Graeme Souness.
With three national titles, a Copa Libertadores and an Intercontinental Cup to their name, the Flamengo side of the early 1980s can also be considered one of the greatest in history.
Led by magnificently talented attacking midfielder Zico, it was a team that combined great passion with wonderful, technically gifted players. The vast majority of the side were products of the Rubro-Negro academy system.
Behind Zico were central midfielders Adilio and Andrade, who provided industry and composure to the side in the centre of the park.
It was a formidable combination that played a major role in the club's successes, while, further forward, wide attacker Tita was among the most renowned in his position of the time.
Left-back Junior was, though, the second most renowned member of the side and would become one of the most capped wing-backs in Brazil's history. A wonderful free-kick taker, he added much to the side from wide positions.
Zico, Junior and Adilio.
Three European Cup titles and three Serie A titles under coaches Arrigo Sacchi and Fabio Capello mean that the AC Milan side of 1988-94 is another side rightfully in contention for the title of "best ever."
Having been saved from financial difficulty by Italian businessman and politician Silvio Berlusconi, Milan invested in the Dutch trio of Frank Rijkaard, Ruud Gullit and Marco van Basten, all of whom played a major role in the club's successes.
Their talents were then complemented by an Italian core of undisputed quality in Franco Baresi, Paolo Maldini, Carlo Ancelotti, Mauro Tassotti and Alessandro Costacurta.
While the team would change much in personal over the time period in question, with the three Dutch players mentioned all moving on or retiring, the success was sustained with Zvonomir Boban and Marcel Desailly among those to come into the side.
Frank Rijkaard, Ruud Gullit and Marco van Basten.
Louis van Gaal's great Ajax side of the mid-1990s was one of football's great success stories, with a team of predominantly academy-produced talents making the final of the European Cup two years in succession.
The club's period at the top of the European game would only be brief, with many of their young talents soon to be sold to clubs across the continent's biggest leagues. However, it will be fondly remembered for many years to come.
It was a side that gave the European game, among others, Frank de Boer, a masterful central defender, and his brother Ronald, a fine goalscoring attacking midfielder.
Alongside him in midfield starred the rising talents of Edgar Davids and Clarence Seedorf, while Mark Overmars and Patrick Kluivert joined Jari Litmanen in a gloriously talented attack.
In goal, of course, was Edwin van der Sar, who would go on to enjoy a great career with Juventus, Fulham and Manchester United, while Nigerians Finidi George and Nwankwo Kanu also added much quality to the side.
Interestingly, many of the side's stars have now returned to work at the club over the past few years.
Frank de Boer, Clarence Seedorf and Jari Litmanen.
Juventus would reach three consecutive Champions League finals between 1996 and 1998 but end up with just one title to their name thanks to defeats to Borussia Dortmund and Real Madrid.
They would, though, also add an Intercontinental Cup and two Serie A titles to their tally, to ensure that the Marcello Lippi era will live long in the memory in Turin.
While the side that won the title in 1996 featured the likes of Fabrizio Ravenelli and Gianluca Vialli, Lippi would immediately bring in Zinedine Zidane, Edgar Davids and Filippo Inzaghi to freshen up the lineup.
The rejuvenated side would twice come close to repeating their predecessors' success but fall at the final hurdle. Domestically, though, it was a different story as the club swept to title glory.
Didier Deschamps anchored the midfield wonderfully, while Ciro Ferrara was an immovable object at centre-back.
However, it was the technical brilliance of Zidane and trequartista Alessandro Del Piero in attack that made this iteration of Juve such a special side.
Zinedine Zidane, Alessandro Del Piero and Ciro Ferrara.
The only club to make this list twice, fittingly, is nine-time European champions Real Madrid, for the period between 1999 and 2003, at the very start of president Florentino Perez's "Galactico era."
Over the four-year spell, Real won the La Liga title twice and captured two European crowns to add to their sizable collection. At the centre of it all were star names Raul, Zinedine Zidane (in 2002) and Roberto Carlos.
There were changes to the side between the two successes, with the addition of Zidane and Portuguese winger Luis Figo most notable, but it was still an evolution of one particular team.
This was, after all, still before the dumping of local players for the arrivals of Ronaldo, David Beckham and many others over the next few seasons.
It was little striker Raul—the top Champions League goalscorer of all time—who encapsulated the side. He had magical footballing ability and an unceasing desire to win. He spent his career in Madrid surrounded by greats, but the local boy was among the very best—scoring in both the 2000 and 2002 finals.
The addition of Zidane in midfield added an elegance to proceedings, while the brute force of Roberto Carlos on the left flank was always a site to behold. They were not infallible, but it was one of the truly great football teams.
Raul, Zinedine Zidane and Roberto Carlos.
Three Premier League titles in four years, as well as a second Champions League title, make this iteration of Alex Ferguson's Manchester United side the best of his reign.
Had it not been for the truly great Barcelona of Pep Guardiola, they may well have emerged from two more Champions League finals with more silverware to their name.
It was a side with immense quality in all areas. From goalkeeper Edwin van der Sar, through Rio Ferdinand, to the likes of Carlos Tevez and Wayne Rooney in attack, United had some of European football's best players of their era.
The core of the side, though, was its strongest area. Serbian rock Nemanja Vidic was arguably the best defender around for a couple of seasons, forming a fine partnership with Ferdinand.
In midfield, meanwhile, veteran Paul Scholes orchestrated proceedings for the likes of Nani, Ryan Giggs and Rooney in wide areas.
Ahead of all that, for the early seasons of the side's success, was Portuguese phenomenon Cristiano Ronaldo, who would eventually cost Real Madrid £80 million to prize away from Old Trafford. A truly incredible side, indeed.
Cristiano Ronaldo, Nemanja Vidic and Paul Scholes.
Pep Guardiol- era Barcelona are a side often touted as the best side in footballing history, although there will be many who disagree with that assertion. Either way, there is no denying they were, and still are, a wonderful footballing side.
The peak of their footballing powers came in a three-year period between 2008 and 2011, winning two Champions League titles in that spell. Only the resilient Inter Milan of Jose Mourinho could deny them three straight titles.
Their high-pressing, tiki-taka style took the footballing world by storm and prevented Alex Ferguson's Manchester United from dominating European football over that period.
Guardiola set about rejuvenating the star-studded side of the Rijkaard era. Out went Ronaldinho, Deco and eventually Samuel Eto'o, with the likes of Sergio Busquets, Pedro and Gerard Pique coming into the first-team setup.
The gamble paid off royally, and the Catalan side firmly established themselves as the benchmark in world football.
Midfield stars Andres Iniesta and Xavi were the side's undeniable heartbeat, and Argentine wonder Lionel Messi has given Barcelona the stardust required to make a truly special side.
Lionel Messi, Xavi and Andres Iniesta.