The Pittsburgh Steelers are one of the most successful teams in NFL history. In fact, their 636 wins are the fourth-most victories in the history of the league.

They are behind only the New York Giants, Green Bay Packers and Chicago Bears, all teams that have played at least 100 more games than Pittsburgh.

At the same time, the Steelers have six Super Bowl wins. That is tied for the most all-time with the New England Patriots.

Clearly, there have been a lot of triumphs for this franchise. However, that does not mean there haven't been some struggles as well.

With that in mind, let's take a look back at the top-five most heartbreaking moments in Steelers' history.

5. 2001 AFC Championship

As we've already mentioned, the Steelers win a lot. Due to that, they tend to find themselves deep in the playoffs. While that's great, it also can lead to some very heartbreaking moments.

With that in mind, we start our list in the 2001 season, with the AFC Championship game.

That game pitted the Steelers against the Patriots, two of the most successful franchises of all time.

Early in the fourth quarter New England kicked a field goal to take a 24-17 lead. There were over 11 minutes left at that point, giving Pittsburgh plenty of time to tie it up.

Instead, the score never changed and a Pittsburgh team that went 13-3 in the regular season was heading home instead of making it to the Super Bowl.

4. 1994 AFC Championship

Next up is the AFC Championship game from the 1994 season. This time, the Steelers found themselves face-to-face with the then-San Diego Chargers.

This time, Pittsburgh finished the regular season with a 12-4 record.

After the first quarter, the Steelers were up 7-0. They then extended their lead to 10-3 after the second quarter. After three quarters, Pittsburgh still had a 13-10 lead. The Chargers then scored a touchdown to go up 17-13 with just over five minutes left in the game.

That was the end of the scoring and Pittsburgh was heading home just short of a trip to the Super Bowl.

3. 1997 AFC Championship

Two years later, the Steelers were right back in the AFC Championship. Once again, they had a different opponent. This time Pittsburgh was squaring off with the Denver Broncos.

Pittsburgh was 11-5 in the regular season that year. First, they managed to squeak by the Patriots in the Divisional round.

Then came the AFC Championship game. Denver jumped to a 24-14 lead at the half. However, the Steelers scored with nearly three minutes left in the game to make it 24-21. However, that's where the rally stopped.

Pittsburgh's defense could not stop a loaded Denver offense and the Broncos managed to run out the rest of the clock. This was yet another year where the Steelers got so close to the Super Bowl but could not manage to get there in the end.

This one also hurt a little more because it was so close to another AFC Championship loss just two years prior.

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2. Super Bowl XXX

Now we are into the Super Bowls. Pittsburgh has lost two of them in the history of the franchise. The first loss came in the 1995 season against the Dallas Cowboys.

This one hurts for a few reasons. First, it was just a year after Pittsburgh dropped the AFC Championship, making it two straight seasons of almost making it but falling at the last moment.

Then there is the obvious fact that it was the Super Bowl, the ultimate goal for every NFL team.

Pittsburgh lost, 27-17, though it was a one-score game in the fourth quarter.

The Steelers scored a touchdown with around seven minutes left to put the score at 20-17. They then got the ball back with a chance to tie or take the lead.

However, an interception not only gave the Cowboys the ball back, but positioned them right next to the end zone. Two plays later, they scored to make it 27-17 with under four minutes to go. Pittsburgh never came back.

That adds some extra heartbreak. Pittsburgh clawed back into it and had a chance, but a turnover derailed the momentum in the game's waning minutes.

1. Super Bowl XLV

Finally, we come to the most recent Super Bowl loss for the Steelers. This came during the 2010 season, against the Green Bay Packers.

This was a loaded team that went 12-4 in the regular season. However, they were having problems in the Super Bowl.

Green Bay was up 21-10 at the half. That's when Pittsburgh made a push.

The Steelers managed a touchdown in the third quarter. This made the score 21-17 heading into the fourth quarter.

Green Bay quickly scored in the fourth, though, extending their lead to 28-17. However, the Steelers responded fast as well, and with a two-point conversion were down just 28-25 with 7:40 left to go.

The Packers scored a field goal to make it 31-25 with 2:10 left in the game. From there, the Steelers tried to put together a drive. It stalled out after a few big plays, spelling the end.

This one was particularly rough because of the multiple comeback efforts. Add on the fact Pittsburgh has not reached the Super Bowl since, and this stings a little bit extra for Steelers fans.