BOSTON — From afar, Al Horford has always had respect for the history of the Boston Celtics.

He made his first visit to the Garden as a rookie in 2007 and found himself drawn to the championship banners that hung above the court.

That was the same season that Kevin Garnett and Ray Allen joined Paul Pierce to form the Big 3 and went on to win Boston’s 17th NBA championship.

As the Celtics biggest free agent signing since then, Horford – with his four-year, $113 million contract – is now the centerpiece of the franchise as it chases banner No. 18.

He enters the 2016-17 campaign no longer the wide-eyed rookie that arrived in Atlanta nine years ago. He’s now a veteran four-time All-Star that team president Danny Ainge believes can provide leadership to a young core led by Isaiah Thomas, Avery Bradley and Jae Crowder. The immediate goal is to help Boston advance past the first round of the playoffs for first time since 2012.

“I know that I’m gonna help our team be better,” Horford said. “I’m gonna try to come in and try to gel as fast as I can and just make sure that we’re playing at a high level, and that we’re working every day. And we’ll see what happens.”

There’s no denying that Horford joins a team that has been on the upswing under Coach Brad Stevens. Boston won just 25 games his first season in 2013-14 but have improved to 40 and 48 wins the past two, which have included back-to-back playoff berths.

But each of those postseason appearances ended in first-round exits, including a 4-2 loss to Horford’s Hawks last season.

That loss was marred by a hamstring injury to Bradley in Game 1, as well as nagging injuries which dogged Crowder and center Kelly Olynyk.

With all of that behind them, Thomas is anxious to see what this group can accomplish when healthy and with some extra star power.

Aside from providing some help defending the rim and rebounding, Horford’s shooting ability also should open up the floor more for a scoring point guard like Thomas, and improved shooter like Bradley.

The expectation is that Crowder will also be freer to operate with Horford drawing attention in the paint.

There is also No. 3 overall draft pick Jaylen Brown, whose athleticism should fit right in with a group that loves to run the floor.

MAKING ADJUSTMENTS: Probably the Celtics’ biggest loss this offseason was the departure of swingman Evan Turner to Portland in free agency. Aside from being a productive sixth man, he also at times triggered their half-court sets when he was in the game. “That’s a big loss,” Stevens said. “A big loss because of the way he handled the ball, the big shots that he made late in the game, his positional versatility defensively, his everyday workman-like attitude in the gym.”

MINUTES FOR ROZIER: The Celtics were dealt a small blow to their second unit when Marcus Smart suffered a left ankle sprain in their preseason finale. The silver lining is that while he’s out, it will almost certainly mean increased playing time for second-year point guard Terry Rozier. Rozier had his best moments as a rookie on the defensive end, but showed a lot of improvement in his shooting during the preseason.”

INJURY WATCH: Olynyk sat out the entire preseason recovering from arthroscopic surgery on his right shoulder in May. After not being cleared for contact in time to appear in any preseason games, it’s possible he could miss a good chunk of games early in the season. It will mean one less body to relieve Horford, but will give the Celtics opportunities to play smaller at times.