BOSTON >> With a Game 5 win on Monday night the Celtics sealed the NBA title, but Boston had actually been waiting for this moment for over a decade.

Just over five years after the Celtics claimed their 17th championship, Boston went into a complete rebuild on June 28, 2013, trading franchise centerpieces Kevin Garnett and Paul Pierce to the Brooklyn Nets in exchange for a package that included role players and draft picks.

What followed was a stretch of nearly 11 years that featured ups and downs, plenty of change and a constant belief that Banner 18 was always just one season away.

Two of the draft picks in the Brooklyn deal ended up turning into Jaylen Brown and Jayson Tatum, drafted third overall in 2016 and 2017, respectively. The Celtics decided to build around the duo, and it ended up being the right choice.

But before the arrival of Brown and Tatum, Boston went through the 25-57 2013-14 campaign that featured Jeff Green as the frontman. Then a 5-foot-9 Isaiah Thomas came to town and started to establish himself as “The Little Guy,” in the words of the late Tommy Heinsohn.

Those teams may not have realized it at the time, but they were laying the foundation for something special.

Once Brown’s rookie season rolled around, the Celtics were really starting to look like contenders. Thomas averaged 28.9 points per game during the 2016-17 season, leading Boston to its first Eastern Conference finals appearance since 2012.

The Celtics came up short but proceeded to load up the following offseason, trading for Kyrie Irving and signing Gordon Hayward. Even though Hayward fractured his left tibia just minutes into his Boston debut, the Celtics ended up returning to the East finals, where they fell to the Cleveland Cavaliers in seven games.

From there, Boston overcame a fallout with Irving and an underwhelming two seasons with Kemba Walker running the point to punch its ticket to the Finals in 2022. Heartbreak was again in the cards, though, as the Golden State Warriors raised the Larry O’Brien Trophy after beating the Celtics in six games.

After getting bounced in the Eastern Conference finals once more a year ago, Boston went all in.

The Celtics parted ways with fan favorite Marcus Smart, considered by many to be the heart and soul of the team, to acquire Kristaps Porzingis via trade, and they also made a deal with the Portland Trail Blazers to bring in Jrue Holiday.

Those moves paid off, and now a league-record 18th banner will be raised this fall.

While this year’s team was the one that broke a 16-year title drought, Celtics coach Joe Mazzulla is forever thankful for Green, Thomas, Smart and every other player that checked in for Boston over the past 11 seasons.

“I think the most important thing, something that’s really been going through my mind throughout this process, is you can’t lose sight of the people that came before us,” Mazzulla said. “And I want to make sure every person that’s worked for the Celtics, that’s played for the Celtics that didn’t win, knows that their work and what they have done has not gone unnoticed or it doesn’t play a part in where we are at today.

“It can be so easy when you work for this organization and you don’t win that the work that people put in just gets brushed over or gets ignored. … So I think that’s one of the first things that came to mind, was just because we won this doesn’t mean what the people have done before us isn’t just as important.”

Through everything over the past seven years, Brown and Tatum have been the one constant.

“We’ve been through a lot, the losses, the expectations,” Brown said. “The media have said all different types of things: We can’t play together, we are never going to win.

“We heard it all. But we just blocked it out, and we just kept going. I trusted him. He trusted me. And we did it together.”

Brown was named Finals MVP. He averaged 20.8 points, 5.4 rebounds and 5.0 assists in the series, and Tatum quickly shot down any notions of him being jealous of his co-star.

“Extremely happy for him. This is a hell of an accomplishment,” Tatum said. “The main goal for us was to win a championship. We weren’t — we didn’t care who got Finals MVP. I know that I need him through this journey, and he needs me.”

The Celtics had plans to fly down to Miami today to celebrate for a bit before returning to Boston for their championship parade on Friday morning. And if all goes to plan, Celtics fans should get used to lining the streets and watching the city’s duck boats roll by.

“I think we definitely have a window,” Brown said. “We take it one day at a time. We definitely have to make sure we stay healthy. But, you know, we’ll enjoy the summer, enjoy the moment, and then we get right back to it next year.”