WALTHAM, Mass. -- The first time Al Horford visited TD Garden -- just five games into his NBA career -- he couldn't stop looking skyward at the Boston Celtics' 16 championship banners that hung above the parquet floor. Horford admits he was hypnotized by the symbols of Boston's winning tradition. He ultimately made six trips to Boston that season as the Celtics defeated Horford's Atlanta Hawks in a thrilling seven-game series in the first round of the Eastern Conference playoffs en route to claiming a 17th world title.

Nine years later, the 30-year-old Horford wore his new Celtics No. 42 jersey at Monday's media day and detailed how Boston's history played a factor in his decision to sign a blockbuster four-year, $113 million deal this past summer.

"Maybe some guys feel differently, but I couldn’t stop looking at [the banners]," Horford said. "It’s powerful. ... This is a special place."

With the scoreboards at the team's practice facility decorated with the same "18"s that have glowed at big media events since the team's last title season, Horford and his new teammates stressed that they would not be overwhelmed by the heightened expectations that greet the team in coach Brad Stevens' fourth year at the helm.

The Celtics, coming off a 48-win campaign and having added Horford this offseason, have been pegged to push north of 50 wins and emerge as the biggest challenger to the defending champion Cleveland Cavaliers in the East. While Stevens and president of basketball operations Danny Ainge were careful to temper expectations, even Ainge conceded there is one ultimate goal in Boston.

"We’re always gearing toward a championship," Ainge said. "That's always our objective. We're building towards a championship. So we need to take another step."

The Celtics haven't made it out of the first round of the playoffs in either of the past two seasons, so title aspirations might be a bit ambitious. Boston found itself at the mercy of a four-way tie-breaker last season that forced the Celtics to go on the round to open the playoffs, where Horford's Hawks elbowed them out in six games.

Listening to Celtics players on Monday, the floor of expectations starts this season at securing home-court advantage in the playoffs and making it out of the first round. But neither Stevens nor his players wanted to put a ceiling on what this team could accomplish.

"The goals for this team is: The sky is the limit," third-year guard Marcus Smart said. "As long as we work hard and do what we're supposed to do and stay together, then anything is possible in the words of the great [Kevin Garnett]."

The Celtics acknowledge they don't have the most pure talent in the league, but they believe their depth and chemistry could help this team distinguish itself. Avery Bradley, the longest-tenured member of the Celtics and the only player who dates back to the Big Three era, was asked whether Boston truly had enough talent to compete with the league's top dogs like the Cavaliers and Golden State Warriors.

"For any team to think they are not [capable of competing with the top teams], I mean, what are you playing this game for?" asked an incredulous Bradley. "Every team should feel like it's 0-0. No one has played a game yet. Every team should feel like they are going to have a chance to win a championship."

Bradley is typically the team's beacon of optimism. But All-Star point guard Isaiah Thomas thinks it's possible for his team to make a leap this season.

"We’re not that far away -- not a championship, we're not that close [yet] -- but we know we can compete with everyone in this league, whether it's Cleveland or Golden State. Those top teams. We know we're right there; we just have to put it all together," Thomas said. "We know we’re a special group. There's a lot of anticipation and expectations, but we're not worried about that. We're worried about things we can control. We have to be ourselves -- whatever is your role, do it at the highest possible level. We have a great group of guys."

Thomas led Boston's recruiting brigade this summer and persuaded Horford to come to Boston before putting a hard sell on Kevin Durant, even if he ultimately chose to take his talents to Golden State.

Thomas is eager to prove he deserved his own leap to All-Star status last season. He thinks Horford's addition is the sort that can push Boston to another level, and he's hell-bent on making sure this team makes progress.

"The whole offseason, that’s all I thought about. Losing that [first-round] series left a bad taste in all of our mouths," Thomas said. "We want to get past that first round. I do, I know that. I want to go further. We have a good team and people to make that happen.

"Last season hurt me, especially because that’s the first time I can say I gave everything I had. I had no more left in me, and that's why I hurt so much. Having everybody back for another year, we're looking for bigger and better things. What that may be we don’t know, but hopefully we can jell faster than we did last year with the additions we have on this team."

For his part, Horford is subscribing to Stevens' one-day-at-a-time philosophy. The banners are the end game, but he's just eager to get to work each day with those banners as motivation on the wall at Boston's practice facility.

"The playoffs are not just given to you. It’s something you have to earn," said Horford, who made nine postseason trips in nine seasons with the Hawks. "You have to work your way into [the postseason]. We can't think that far ahead. Our biggest thing is to handle our business now. I'm looking forward to getting to that first two-a-day [practice on Tuesday], starting to work with the guys and just start building that chemistry. That's what I'm more concerned about."