From signing Henry to Dein's departure - The 20 defining moments of Wenger's Arsenal reign

When Wenger arrived in north London, he completely changed the entire culture of the club.

New training regimes based around isometrics helped older players such as Tony Adams and Martin Keown prolong their careers.

Indeed, diets changed dramatically as Wenger introduced healthy food into the club canteen and his revolutionary methods immediately reaped dividends, as he won the double in his first full season as manager.

Wenger was widely lauded for his sense of fair play when, in February 1999, he offered an FA Cup rematch to Sheffield United because Marc Overmars' decisive goal in a 2-1 win at Highbury had come while one of the visiting team's players was down injured.

The rematch took place 10 days later and Arsenal won again by the exact same scoreline.

The loss of striking sensation Nicolas Anelka to Real Madrid in the summer of 1999 looked like a major blow for Arsenal but Wenger used the £23m accrued to sign Thierry Henry, which proved an absolute masterstroke.

Emmanuel Adebayor, Emmanuel Petit, Marc Overmars and Alexander Hleb also feature among the list of players that were never quite the same again after leaving north London.

After arriving from Juventus in August 1999 for £11 million, Henry was converted from a winger into a striker by Wenger, who had previously worked with his fellow Frenchman at Monaco. 

The rest, as they say, is history, with Henry going on to become Arsenal's all-time record goalscorer, as well as one of the finest centre-forwards of the modern era.

His return in 2012 was not quite as successful but there was sheer jubilation when he scored an FA Cup winner against Leeds.

As well as having a keen eye for raw talent, Wenger is also renowned for successfully changing a player's position.

The aforementioned Henry is obviously the most famous success story, but Wenger also converted Lauren from a midfielder into a fine right-back, and made Emmanuel Petit, who had been regularly used on the left-hand side by Monaco, a world-class defensive midfielder.

Most recently, Hector Bellerin was converted from a right winger to a full-back, with assistant manager Steve Bould having played a huge part in helping the Spanish starlet improve his defensive game.

Wenger versus Ferguson, Keane versus Vieira, Keown versus Van Nistelrooy - Arsenal versus Manchester United remains arguably the greatest and most volatile rivalry the Premier League has ever seen.

Their games may no longer be as heated as they once were but, for so many years, this was the must-see fixture in English football, with so many clashes on the field - and off it... see 'Pizzagate' for further information!

Martin Tyler's commentary still resonates in the minds of Arsenal fans everywhere: "Pushed out by Barthez... WILTORRRRRD!" 

Arsenal had arrived at Old Trafford at the tail end of the 2001-02 season knowing that victory over second-placed Manchester United would seal the title but star striker Henry was unavailable through injury.

However, compatriot Sylvain Wiltord stepped up to the mark, slotting home a rebound from a Frederik Ljungberg shot to send the visiting supporters wild!

Arsenal would have been eliminated from the Champions League had they lost away to Inter on matchday day five of the 2003-04 group stage.

However, they responded to adversity in sensational style by recording one of the most memorable victories in the club's history, triumphing 5-1 at San Siro, with Henry netting twice during an attacking masterclass up front.

Indeed, the Frenchman's second goal - which came after he had left the legendary Javier Zanetti trailing in his wake - remains one of the most iconic strikes of Wenger's reign.

There have been various famous victories over Tottenham throughout Wenger's reign as Arsenal manager but their most fondly remembered result is the 2-2 draw that clinched the 2003-04 title at White Hart Lane.

To this day, Arsenal fans sing chants about being crowned champions in their neighbours' own backyard!

'The Invincibles', Wenger's masterpiece, an unstoppable, irresistible force that swept all before them during 2003-04 Premier League campaign.

Indeed, that Arsenal side is regarded as one of the finest in English football history, not only because they went undefeated but because they did so with a style and panache that had never been seen before.

Wenger's biggest regret as Arsenal manager is not winning the Champions League during his time in charge, particularly having gone so close in 2006.

Despite having Jens Lehmann sent off in the final against Barcelona, the Gunners still managed to take the lead, when Sol Campbell headed home a Thierry Henry cross.

They could have doubled their advantage too, but Henry shot straight at Victor Valdes, and that squandered opportunity proved crucial, as a Henrik Larsson-inspired Barca turned the game around in the closing stages through Samuel Eto'o and Juliano Belletti, leaving Wenger and his troops heartbroken.

More than a decade on from moving to the Emirates, the decision to build a new stadium has been proven to be correct.

Arsenal have suffered in the short term with a relative lack of silverware but the commercial opportunities now available to the club have put the Gunners among Europe's elite in terms of revenue.

The move was pioneered by the late Danny Fiszman and Wenger himself.

Emirates Stadium's first real 'big' game: Arsenal versus Manchester United on January 21, 2007.

The league-leading vistors took the lead through Wayne Rooney but Robin van Persie equalised with just seven minutes remaining.

The crowd then went wild when Henry headed in a last-minute winner and Arsenal's new stadium began to feel a lot more like home.

David Dein suddenly walking away from the Emirates in April 2007 after a boardroom bust-up was bad news for Arsene Wenger, who had been hired by Arsenal's then vice-chairman 11 years previously.

Dein was renowned for being a slick negotiator and he was responsible for the arrival of some of the most important players of Wenger's reign.

He was succeeded by Ivan Gazidis in 2008 but there is no doubt that Wenger missed his right-hand man alongside him during the less-successful second half of his tenure.

It may have ended in all-too-familiar European disappointment but Arsenal's 2010-11 Champions League last-16 tie with Barcelona was an epic affair.

Despite falling behind to a first-half strike from David Villa in the first leg at the Emirates, the Gunners came storming back to beat one of the best teams in history with late goals from Van Persie and Andrey Arshavin.

Arsenal bowed out after losing the return leg at Camp Nou 3-1 but the win in north London remains one of Wenger's finest hours, as he went toe to toe with Pep Guardiola, and came out on top.

A depleted, injury-ravaged Arsenal side were infamously torn asunder by great rivals Manchester United at Old Trafford in August 2011.

The 8-2 humbling ranks as one of the darkest days of Wenger's career and one which the supporters present are unlikely to ever forget.

Wenger has been nothing if not loyal. It's rare in today's world to see anyone stay in a job for 20 years, let alone a football manager.

And particularly one as revered as Wenger, who has turned down offers from Bayern Munich, Paris Saint-Germain and Real Madrid over the years.

Mesut Ozil joined from Real Madrid for a record fee of £42.5m in 2013 and Alexis Sanchez followed from Barcelona a year later.

Both were marquee signings which emphasised the transition from bargain-basement arrivals to genuine world-class additions.

They failed to help Arsenal win the league but both made a huge impact at the Emirates.

Nine years without a trophy came to an end with a toe-poke from Aaron Ramsey in an absorbing FA Cup final clash with Hull City in 2014.

It may not have been the most beautiful goal but it was one of the most important of the second half of Wenger's tenure, as he could well have resigned had the Gunners not beaten The Tigers, who had raced into a 2-0 lead.

However, Santi Cazorla promptly pulled one back for Arsenal before Laurent Koscielny forced extra-time, where Ramsey popped up with the winner.

The final few years of Wenger's reign had been tarnished by increasingly bitter fan protests but when he finally decided to say goodbye, he was given a hero's send-off at the Emirates Stadium.

After Arsenal had produced a fittingly fluid performance in routing Burnely 5-0, Wenger took centre stage, telling the crowd, “I would like to finish in one simple sentence: I will miss you.”

Arsenal, and indeed English football, will miss him too.