Every football club in the world wishes to improve upon their last-season exploits. The teams want to score more, defend better and, ultimately, celebrate wildly after the end of a successful campaign. Unfortunately, the desire to win is not the only prerequisite for success. The transfer market arguably has the most crucial role to play.Reinvigorated by the recently-concluded, highly explosive transfer window, we will be looking at the most noteworthy transfer windows of the century. We will consider the impact of the transfers for the respective clubs, the amount spent on transfers, and more to create a list of five. Now, without further ado, let us have a quick look at5 most spectacular transfer windows of the century#5 Summer of 2000Luis Figo in Real Madrid v BarcelonaThe summer of 2000 was not particularly explosive in terms of money spent. But it still ended up making a massive impact on the sport, changing the way we see politics in football.The summer transfer window of 2000 is infamous for the transfer of Barcelona captain Luis Figo to Real Madrid. Los Blancos presidential candidate Florentino Perez struck a deal with Figo, stating that the Portuguese would have to sign for Real Madrid if Perez won the election. Figo agreed to the deal, thinking it was impossible for Perez, who had no experience in the field, to win the election.Surprisingly, Perez won the election, and signed Figo from Barcelona for €60m, which was a world-record at the time. Barcelona fans were furious with the deal and infamously hurled a pig’s head at Figo during a Clasico at the Camp Nou in 2002.October 2000: Luís Figo came back at Camp Nou for the first time as #RealMadrid player.💣💣💣⚡⚡⚡#ElClasico #LaLiga #RealMadridBarça pic.twitter.com/XJ4uytlRz5— AS English (@English_AS) April 10, 2021Manchester United legend Rio Ferdinand also moved in the same window, signing for Leeds United from West Ham United for €21m. Furthermore, Real Madrid added Claudio Makelele to their roster, who later on went on to redefine the central defensive-midfielder role as a “destroyer.”#4 Summer of 2014Newcastle United v Chelsea - Premier LeagueIn 2014, many top clubs signed world class players, with some paying high dividends down the road.Chelsea signed the likes of Diego Costa (€38m), Cesc Fabregas (€33m), Juan Cudrado (€31m), and Filipe Luis (€20m). They even got their former player Didier Drogba on a free and sent Romelu Lukaku to Everton, with the Belgian striker continuing his development at the Merseyside club. Thanks to their ambition, Chelsea won the Premier League at the end of the season.ON THIS DAY: In 2014, Luis Suárez joined Barcelona from Liverpool for £75m. His record in LaLiga since:🏃 130 games⚽️ 110 goals🅰️ 55 assists 🏆 3 titles pic.twitter.com/Rz9Alz9ao4— Squawka Football (@Squawka) July 16, 2018La Liga club Barcelona broke the bank to sign Luis Suarez from Liverpool, spending €81.72m on the Uruguayan sharpshooter. They also picked up Ivan Rakitic for €19m from Sevilla and Marc-Andre ter Stegen for €12m from Borussia Monchengladbach. Suarez formed a devastating front-three with Neymar and Lionel Messi, while Rakitic became an integral part of the midfield. The Blaugrana completed their second treble of La Liga, Copa del Rey and the UEFA Champions League at the end of the season.Real Madrid, too, signed Toni Kroos (€25m) and James Rodriguez (€75m) from Bayern Munich and AS Monaco, respectively. The former is serving the club diligently to this day and has cemented his place in Real Madrid's illustrious history.