Of all the Irish taverns in the Irish town of St. Paul, O’Gara’s Bar & Grill offers the deepest dose of nostalgia.

Since 1941, St. Patrick’s Day revelers have flocked to the family-owned pub at the corner of Snelling and Selby avenues to imbibe under pressed-tin ceilings and historic photographs.

“It doesn’t have all the bells and whistles of new bars,” said Texas transplant Chas Teeter, who’s counted himself a regular for 16 years. “We love the old charm.”

But change is coming to the neighborhood staple, whose operators plan to raze the 110-year-old building and replace it with a mixed-use apartment complex and a downsized watering hole. “O’Gara’s is not going away,” said third-generation owner Dan O’Gara. “We’re just reinventing ourselves.”

Yet, on this St. Paddy’s Day — the very last for the historic structure — a sea of green-clad patrons packed the marble-topped bar area and massive outdoor tent to mark the end of an era. Between sips from pints of Guinness, longtime customers reminisced about their first taste of corned beef and cabbage from the kitchen and the days when bands played six nights a week.

For 20 years, Dennis Welch and his buddy Greg Kennedy have maintained a standing get-together at O’Gara’s on St. Patrick’s Day. No need to call or text, just meet at noon. “It’s a reunion for these two,” said Welch’s wife, Lisa. “They could go 10 months without seeing each other and it wouldn’t matter.”

The friends were drawn to the location, far enough from the madness of downtown, with its outdoor seating and bagpipe music.

“You can actually get a drink,” said Welch, nursing a Jameson Irish whiskey and soda. The tradition stuck, and now they take every March 17 off work. Sometimes the next day too, just to sleep it off.

Other regulars say the bar’s name recognition makes it an obvious place to start their annual bar crawl. Morning shuttles ferry people to the St. Patrick’s Day Parade downtown, then back in the afternoon. Those who show up by 3:30 p.m. can catch the “World’s Shortest St. Patrick’s Day Parade,” a 28-foot procession that starts at the tavern’s back door and snakes through the bar.

Judy Niemann and Colleen McNellis, of Hugo, found themselves drawn to O’Gara’s Saturday for one last hurrah. The sisters were raised two blocks away on Hague Avenue, where they used to tag along with their father as he plopped down for a cold one. They’ve patronized the site for the past 70 years and watched it expand over time.

“It’s just nostalgia and memories for us,” said McNellis, 74. “Once you get older, those memories are the best thing you have.”

Several generations of the McNellis clan have marched in the downtown parade, then continued on to the merriment at O’Gara’s. Now they worry that a new establishment just won’t have the same allure. But they’ll give it a chance.

“It’ll never be the same,” said Niemann, 78, sipping on a rum and Coke. “We had to be here today.”