For the estimated 2 million attendees according to APat the St. Patrick’s Day parade Tuesday, it was more than a chance to be part of a celebration, it was an opportunity to witness history.

OUT@NBCUniversal became the first LGBTQ organization permitted to openly march in the parade’s history.

The group, made up of about 100 LGBTQ employees of the parade's broadcaster NBCUniversal, marched up Fifth Avenue around 3:30 p.m. to cheers and applause.

“It's exciting to celebrate our love for Ireland and our love for equality,” said Caitlin Harris, 18, of Greenwich Village as she watched the parade with her mother.

The celebraton began in the morning as revelers, who were decked out in green from head to toe, lined up Fifth Avenue to check out the dozens of marchers, bagpipers, dancers and others who took part in the 254th parade. Cardinal Timothy Dolan served as the grand marshal and greeted paradegoers with handshakes throughout the march.

“It’s a great show of New York pride, the pride of St. Patrick and the energy of the city,” said Mary Hieronymi, 53 of Moriches. “You can’t beat it.”

advertisement | advertise on newsday

Longtime revelers say the city's celebration of the Catholic holiday is unlike any other throughout the world because of its sheer size of participants.

“I'm truly impressed by the school marching bands, there's a lot of them this year,” said Joe Sullivan 24, of Manhattan, “They add some form of variety.”

Many parade goers were not of Irish descent but said they wanted to take in the days festivities. Monique Lazaruk, 16, of Toronto, came to the parade for the first time with her family and said she enjoys seeing Irish dance performances.

“This doesn't really happen back home,” she said.

For the second year in a row, the parade went on without Mayor Bill de Blasio and the whole City Council. The mayor and Council Speaker Melissa Mark-Viverito said the inclusion of OUT@NBCUniversal was a a positive change, but they were disappointed other LGBTQ groups weren’t allowed to march. The St. Patrick’s Day parade organizers said they would look at applications from the groups for the 2016 march.

Get the Newsday Now newsletter!

The best of Newsday every day in your inbox.

The mayor did, however, attended the annual mass at St. Patrick's Cathedral – arriving about 15 minutes late.

De Blasio, who has been criticized for being frequently tardy to  events since becoming mayor, said he wasdelayed by the St. Patrick's Day breakfast at Gracie Mansion earlier in the morning that ran past schedule. The breakfast ceremony started late, a mayoral spokesman said, because de Blasio met first with a smaller group, including the day’s honoree, former newspaper columnist Pete Hamill, and other dignitaries, “and the morning’s program ran longer than anticipated.”

“I think the moral of the story is, we're going to start the breakfast even earlier next year, because that's a little bit of a tight time frame we have. We have to do better next year,” de Blasio told reporters later in the day.

Irish Queers, an LGBT rights group, rallied at 57th Street and 5th Avenue during the parade and held a huge green banner that read, “Let gays into Irish Parade."

"We're here to demand inclusion,” said group member Emmaia Gelman. “We're not going to take half measures.”

advertisement | advertise on newsday

Despite the protests, some revelers said they were happy that the parade did take a step forward and hoped organizers would continue to make the festivities more inclusive.

“We’ve been waiting for this to happen for years,” said Eileen Coyne<NO1> caitlin harris’s mom declined to give age<NO> of Greenwich Village.

-with Matthew Chayes