Packing the roads from City Hall Plaza to Causeway Street, Celtics fans arrived to celebrate Banner 18 early while carrying the “highest expectations ever” for the season ahead.

Celtics diehard KJ Green has never seen a banner go up into the rafters and he said he won’t be surprised if tears flow out of his eyes as it rises. He skipped getting an energy drink on his way to the TD Garden and looked forward to riding the “absolute adrenaline” in the arena.

Green has become an icon in Celtics Nation. Kristaps Porzingis recognized Green’s passion days after the Green and White won Banner 18 in June, picking the fan to ride along with him during the Duck Boat parade.

“The Celtics are going to be a powerhouse,” Green told the Herald outside the Garden. “Nobody is going to be able to mess with the Celtics this year. We have the best fans in the entire world, and tonight the world is watching. We are going to go wild in there.”

Blocks away from the Garden, fans flocked to City Hall Plaza for the NBA on TNT American Express Road Show that drew the Inside the NBA studio team of Ernie Johnson and NBA legends Charles Barkley, Kenny Smith, and Shaquille O’Neal.

Outside City Hall, the festivities included a pregame musical performance by country star Shaboozey and a post-game concert by pop singer Benson Boone.

Kevin Garnett and Paul Pierce, superstars who guided the Celtics to Banner 17 in 2008, also hosted a live episode of the podcast right outside the Garden at Big Night Live, hours before the franchise’s next banner rose to the rafters.

A healthy dose of fans attending Tuesday night’s Banner Night was in the building when the team hoisted the Larry O’Brien trophy in June when the Celtics defeated Dallas in Game 5 of the Finals.

Dracut resident Tommy Cruickshank was one of those fans.

“I can’t explain it,” he said of how he felt when thinking about Banner 18 rising into the rafters.

Gov. Maura Healey declared Tuesday as Celtics Banner 18 Day in Massachusetts. She highlighted how last year’s team “featured outstanding individual achievements” in a proclamation on Monday and

“The Celtics’ continued excellence brings joy to the residents of Massachusetts and basketball fans around the world,” part of the proclamation read, “their commitment to hard work and team unity offers a powerful example to young people, and their devotion to community uplifts our state, reflects our shared values, and makes us proud.”

Donning a green suit jacket and green top hat with pictures of current and former Celtics, superfan Maryellen Cahill held a mini NBA Finals trophy that she got at the mall over the summer.

“It’s electric,” Cahill, a volunteer with the Shamrock Foundation, said of the atmosphere outside the Garden. “They’re going to win it again. They have the best fanbase.”

Winchester resident Matt McCarthy, 17, also attended Game 5 in June, with his family being season ticket holders for several years. He believes the Celtics have what it takes to win it all again this year.

“I am a diehard fan,” he said. “I go crazy every game. I’m super excited for this, I can’t wait to see the first banner of my lifetime.”

His mother Jen added: “For me, seeing Matthew get to see a championship is amazing. I’ve never been happier for him.”

Fans cheer during a Celtics rally on City Hall Plaza. (Nancy Lane/Boston Herald)
Calvin Lau shows off his team regalia during a Celtics rally on City Hall Plaza. (Nancy Lane/Boston Herald)
Jennifer Marquez holds her son, Arcturus Marquez-Johnson,5, during a Celtics rally on City Hall Plaza. (Nancy Lane/Boston Herald)