Paris Saint-Germain's 2021 summer transfer window has been nothing short of incredible.
The Ligue 1 outfit have signed Lionel Messi, Sergio Ramos, Gianluigi Donnarumma and Gini Wijnaldum on free transfers, while also bringing in Achraf Hakimi for around £51.3m.
After acquiring players of that calibre, PSG will be expected to dominate on all fronts in the 2021/22 season - the Champions League in particular.
The French side's activity in the transfer market this summer got us here at GIVEMSPORT thinking about other times in the 21st century when a big club has enjoyed a hugely successful window.
So we decided to do some research to find 11 more instances of major European teams doing just that and you can check out our choices below.
Chelsea sign Romelu Lukaku | Football Terrace
Of course, not every single signing made by the teams in the year in question was successful, but most were.
All transfers fees sourced from the ever-reliable Transfernarkt.
Roma | 2000
Notable signings: Gabriel Batistuta (£32.54m), Walter Samuel (£18.72m), Jonathan Zebina (£16.56m), Emerson (£13.20m)
In the summer of 2000, Roma bolstered what was an already star-studded squad with some elite signings and it resulted in the team winning the Serie A title in 2000/01. Batistuta, the most expensive acquisition of the bunch, finished the league season with 20 goals to his name.
Juventus | 2001
Notable signings: Gianluigi Buffon (£47.60m), Pavel Nedved (£40.50m), Lillian Thuram (£32.54m), Marcelo Salas (£22.50m), Cristian Zenoni (£13.95m), Nicola Amoruso (£4.95m)
Juve responded to Roma's Serie A triumph in 2000/01 by splashing the cash in the transfer market - and it proved to be a brilliant move. The Bianconeri won the Scudetto in both 2001/02 and 2002/03, with Buffon and Nedved going on to reach legendary status at the Turin club.
AC Milan | 2002
Notable signings: Alessandro Nesta (£27.90m), Clarence Seedorf (£20.55m), Martin Laursen (£9.90m), Rivaldo (Free), Jon Dahl Tomasson (Free)
Don't worry, it's not all Italian teams in this list. Milan's lavish spending in the summer of 2002 didn't result in a league title straight away, but it did help them win the 2002/03 Champions League. The likes of Nesta and Seedorf went on to secure the Serie A crown the following season.
Chelsea | 2004
Notable signings: Didier Drogba (£34.65m), Ricardo Carvalho (£27.00m), Paulo Ferreira (£18.00m), Arjen Robben (£16.20m), Tiago Mendes (£13.50m), Petr Cech (£11.70m), Alex (£10.35m)
Jose Mourinho's first transfer window as Chelsea boss was pretty spectacular. It really was the start of a trophy-filled era for the Blues, with the west London club storming to the Premier League title in 2004/05. As transfer windows by English teams go, this might just be the best in history.
Barcelona | 2004
Notable signings: Samuel Eto'o (£24.30m), Deco (£18.90m), Ludovic Giuly (£7.65m), Edmilson (£7.20m), Juliano Belletti (£5.40m), Sylvinho (£1.35m), Giovanni van Bronckhorst (Free), Henrik Larsson (Free)
After signing Ronaldinho the previous summer, Barcelona decided to flex their financial muscle to help the Brazilian superstar thrive even more. Spoiler alert, it worked. The Blaugrana won La Liga in both 2004/05 and 2005/06, as well as the Champions League in the latter of those two seasons.
Real Madrid | 2009
Notable signings: Cristiano Ronaldo (£84.60m), Kaka (£60.30m), Karim Benzema (£31.50m), Xabi Alonso (£31.05m), Raul Albiol (£13.50m), Alvaro Negredo (£4.50m), Esteban Granero (£3.60m), Alvaro Arbeloa (£3.60m)
Any transfer window when a club signs arguably the greatest player in history has to go down as a stellar one. Ronaldo netted goals for fun at Real Madrid, while both Benzema and Alonso also performed to a world-class standard on a regular basis for Los Blancos.
Inter Milan | 2009
Notable signings: Diego Milito (£25.20m), Samuel Eto'o (£18.00m), Wesley Sneijder (£13.50m), Thiago Motta (£9.18m), Lucio (£6.30m), Goran Pandev (Free)
The transfer window that paved the way for Mourinho's treble-winning campaign at Inter. Milito, Eto'o, Sneijder, Motta, Lucio and Pandev all played key roles in the Italian side's famous 2009/10 campaign and what's more impressive is the fact only one of them cost over £20m.
Chelsea | 2014
Notable signings: Diego Costa (£34.20m), Cesc Fabregas (£29.70m), Filipe Luis (£18.00m), Loic Remy (£11.88m), Didier Drogba (Free)
In Mourinho's second spell as manager, Chelsea acted decisively in the transfer market once again. Costa and Fabregas proved to be the definition of game-changing signings, the Spanish pair guiding the Blues to a 2014/15 Premier League triumph. Remy and Drogba weren't the worst buys either.
Barcelona | 2014
Notable signings: Luis Suarez (£73.55m), Jeremy Mathieu (£18.00m), Thomas Vermaelen (£17.10m), Ivan Rakitic (£16.20m), Marc-Andre ter Stegen (£10.80m)
Suarez, Rakitic and Ter Stegen were all added to Barcelona's roster in the summer of 2014 and the trio were pivotal to the team's treble-winning campaign in 2014/15. All three started the Champions League final success versus Juventus, with Suarez netting the team's second goal that night.
Manchester City | 2015
De Bruyne and Sterling are now seen as two of City's greatest ever players, while Otamendi and Delph were both vital to the club's Premier League title-winning campaign in 2017/18. All in all, the summer of 2015 was a very, very good one for the current English champions.
Liverpool | 2018
Notable signings: Alisson Becker (£56.25m), Naby Keita (£54.00m), Fabinho (£40.50m), Xherdan Shaqiri (£13.23m)
The transfer window that helped Liverpool end their long wait for Premier League glory in 2019/20. Alisson and Fabinho proved to be the missing pieces in Jurgen Klopp's jigsaw and both Brazilians also helped the Reds win the Champions League in 2018/19. There's still time for Keita to come good as well...