Portland observed the Fourth of July on Monday with fireworks, music and a more somber ceremony marking the 150th anniversary of a massive fire that burned and then reshaped the city.

Tens of thousands of spectators gathered on the city’s Eastern Promenade as the sun went down Monday night to watch a more than 30-minute barrage of fireworks light up the waters off the peninsula. The Portland Symphony Orchestra provided the soundtrack during and before the pyrotechnic display at its Patriotic Pops concert, part of the city’s Stars & Stripes Spectacular.

The show drew seasoned veterans from the surrounding neighborhoods as well as newcomers, including a trio visiting Portland from Montreal.

“Fantastic,” said Maria Davila, who watched the fireworks with her fellow Montreal residents Susan and William Lawrence. The three were still sitting on a bench watching fireworks from distant towns and the pleasure boat traffic in Casco Bay about 20 minutes after the Portland show ended.

“It was really spectacular and I kept thinking that there were so many more people here than we’d have in Canada,” Davila added.

Official crowd figures were not available Monday night, but city officials had estimated that 50,000 people would watch the fireworks throughout the city.

Portland’s official Fourth of July commemorations began hours earlier with a historic – if less festive – ceremony in downtown marking an event that forever changed the city by the sea.

On July 4, 1866, a small fire sparked along the waterfront, reportedly by boys playing with fireworks, quickly grew into what was then the largest fire in U.S. history.

At 4:41 p.m. Monday, the steeple bells of Portland’s First Parish Church on Congress Street tolled eight times, paused and then tolled eight more times exactly as they had done 150 years earlier to alert the city’s firefighters to a blaze in the city’s 8th District. By the time the fire had burned out 15 hours later, roughly one-third of Portland was in ashes or smoldering and 10,000 people were homeless.

Speaking during a ceremony just blocks away in Monument Square, historian Herb Adams told of how the Great Fire of 1866 burned 8 miles of city streets, all of the bustling seaport’s banks and newspapers, and nine of its 12 hotels. Four or five people were killed in the conflagration.

“With these ceremonies today, we do not celebrate but we commemorate an event that put one era behind us, opened a new era before us and put our city on a different path, and our citizens as well,” Adams said. “And on that path we still march today. The Great Fire of July 4, 1866, was the largest and most destructive citywide fire in the history of the United States up to that time outside of warfare itself. Only Columbia, only Atlanta, only Savannah knew what Portland knew that night and they under the sword of war.”

Representatives of the Portland Fire Department, whose predecessors battled the Great Fire for hours, also participated in Monday’s ceremonies, including by ringing the bell of Engine 5 after the church bells marked the time when the fire was first reported on Commercial Street 150 years ago. It had been a dry spring and summer in 1866, which meant cisterns, reservoirs and wells were low.

“As they ran out of water, they would unhook the hoses and take a new stand on another location a block away, cutting off the inferno until they had to move again, and again, and again, and again,” said Michael Daicy, historian for the Portland Fire Department. “As the inferno gained strength, they continued fighting the fire for nearly 17 hours, not knowing the fate of their own families or homes and businesses.”

A few dozen people watched the Monument Square ceremony. Tens of thousands of people, meanwhile, gathered on the Eastern Prom for the city’s Stars and Stripes Spectacular.

Organizers incorporated the 150th anniversary of the Great Fire into the evening’s festivities. During opening ceremonies, speakers said the Great Fire “marks a moment of resilience for the city of Portland.” The Portland Symphony Orchestra, meanwhile, paid tribute both to the historic fire of Portland’s past as well as the history being made hundreds of millions of miles away. The symphony performed composer Gustav Holst’s famous piece titled “Jupiter” to mark the 150th anniversary of the Great Fire and the fact that NASA’s spacecraft Juno was preparing to enter the planet Jupiter’s orbit.

Sally A. Deluca, 80, had staked out a prime spot – high above the bay on the sidewalk of the Eastern Promenade – to watch the fireworks. A native of Munjoy Hill, Deluca has been watching the fireworks from what she calls “her hill” since she was a little girl and said she looks forward to them every year.

“It’s just a thrill to me,” said Deluca, who loves the more recent addition of the orchestra. “I sit here and I’m just amazed.”

Deluca said she has been following the news reports about the 150th anniversary of the fire and was certainly aware of the history. But despite the fire’s impact on the city, Deluca said she doesn’t remember it being discussed when she was growing up.

“They didn’t talk about it,” she said. “Back in those days, they just didn’t.”

Most spectators were probably not thinking about that fiery night in Portland 150 years earlier, when flames scorched a path from Commercial Street to the farmfields of Munjoy Hill not far from today’s Eastern Prom. With sunny skies and temperatures in the upper 70s to low 80s, the crowd packed the lawn of the Eastern Promenade and then filled the streets of Munjoy Hill to watch the fireworks display.

Portland police said the July Fourth observances on the Eastern Prom went smoothly overall, despite the crowd. Police made two arrests at the event, for driving to endanger and for theft. No names or additional information was immediately available late Monday night.

The Stars & Stripes Spectacular is paid for entirely with donations and corporate sponsors – including the Portland Press Herald/Maine Sunday Telegram – and does not involve taxpayer funds.

Among the crowd was Steve and Cathy Lyons, along with their son Nikky, who made the roughly hourlong drive from Bridgton, north of Sebago Lake, to see hear the music and watch the fireworks over Casco Bay. The couple have made the trip several times over the years and decided to check out Portland’s show after watching Bridgton’s fireworks a day earlier.

“It’s such a good show,” Steve Lyons said just before the opening ceremonies. “They do a really good job. It’s here by the ocean … and you get a nice sea breeze.”