Arsenal beat the Catalans 2-1 at the Emirates in the first leg of their Champions League round-of-16 encounter back in February.
It was undoubtedly one of the games of the year, with Barcelona taking the lead before goals from Robin van Persie and Andrei Arshavin handed the Gunners victory. Even though they then lost in the return leg in March to the eventual champions, it was one of the best performances by an Arsenal team in recent years.
Speaking to Arsenal.com, Wenger said: "The game against Barcelona was maybe the best game we have ever played on the football pitch here. For me, that was the highlight."
Things went pear-shaped from then with Arsenal losing a catastrophic Carling Cup final to Birmingham, getting knocked out of the Champions League and the FA Cup as well as losing their way in the Premier League title race.
Wenger admitted it had been a harrowing 12 months.
"When I look back, it was not the easiest year of my career. The end of last [season] was even more difficult than the rocky time we had at the beginning of this season because it was all doom and gloom, only negatives.
"This season we had a very tough time too, but we had something in front of us, we could still fight for something.
"With the last two months of last season, once you are in a position where you will not win the Champions League, will not win the league, will not win the FA Cup, you just have to get over the line as well as you can. It was difficult."
Even though Arsenal had a largely forgettable year, Robin van Persie was in the form of his life. The Dutchman smashed in 35 Premier League goals to break the club record of 34 held by Thierry Henry.
Paying tribute to the striker, teammate Mikel Arteta said:"It's obviously something massive to beat the record like that at a club like Arsenal with this history. It's not a small thing.
"You need to have that in your mind if you want to be ambitious but thankfully it's gone now and that might take a bit of pressure off.
"He can keep scoring the goals, he has been fantastic. Nobody else has been as helpful for the team as he's been."
Arteta was also upbeat about the impending arrival of Henry on a two-month loan deal.
"I've always been a big admirer of him, when he was playing here and at Barcelona," said the midfielder.
"It's great to have him around with his experience and his talent - I'm sure he's going to be really helpful.
"He's very good. He's very close with everyone, he's talking with all the lads and has a very, very good attitude.
"I heard a lot of things about him and his character and for being so brave to come back here with the name he has is not easy. He's putting his name on the line yet again and I think that's brave.
"He has the quality and the talent for sure. I don't know how he is physically to play 90 minutes, 60 minutes, 30 or whatever he needs but I think with his experience he can manage that no problem."
Henry has been training with Arsenal at the team's London Colney training ground.