Beyond the multicolored shops, red brick streets packed with performers, and quays filled with sailboats that draw visitors to the town of Kinsale in County Cork, Ireland, is a memorial to a tragedy that occurred an ocean away.

On a hilltop overlooking the fishing village on Ireland’s southwest coast stands a grove of 343 trees — one for each firefighter who died in New York City on Sept. 11, 2001.

Kathleen Murphy, who grew up in Kinsale and immigrated to New York, was working as a nurse at Lenox Hill Hospital in Manhattan when the World Trade Center was struck. Murphy, 56 at the time, treated wounded firefighters and spent the days that followed at ground zero, trying to help in any way she could, her nephew John Murphy said.

But frustration lingered. Even with her skills and training, she felt powerless. So many people died before anyone could save them.

So when she returned to her hometown for a visit shortly after the attacks, she enlisted locals and relatives to help create a memorial garden on an acre plot of family land in a section of town called Ringfinnan. By November 2001, a small grove had formed. On St. Patrick’s Day the following year, the Ringfinnan Garden of Remembrance officially opened.

“After the fact, after the grief surrounding the whole event, it could be something that would be left,’’ John Murphy said.

Kathleen Murphy died in 2011, at age 66, after a five-year battle with ovarian cancer, which her family believes was not connected to her time spent at ground zero.

Today, the young trees planted 22 years ago have grown into mature sycamores and oaks, each shading a sign that bears the name of a firefighter in bold, black print. On Monday, a group of locals — residents, town councilors — gathered in the garden for a quiet moment of reflection.

Over the years, many have come to pay their respects, often traveling great distances to reach the memorial. Just last month, members of the New York Fire Department’s Emerald Society, a group for those of Irish heritage, visited the garden and laid a wreath.

Murphy had been close to the Rev. Mychal Judge, a chaplain in the New York Fire Department and a priest known for his work with AIDS patients.

On the morning of Sept. 11, while administering last rites to firefighters, Judge, 68, was struck by falling debris and died. His death was the first loss recorded that day.

Judge was the son of Irish immigrants and made his first visit to his ancestral home in the village of Keshcarrigan, in the northern county of Leitrim, in 2000. “For all of us here whose parents are Irish born, our DNA is really from Ireland,’’ said the Rev. Christopher Keenan, 81, a friend of Judge’s who took over for him as a Fire Department chaplain.

A firefighting tradition has continued among New York’s Irish families since immigrants began arriving in the city in large numbers in the mid-19th century. John Murphy, 42, said that when he tends to the trees, making good on a promise he made to his aunt over a decade ago, he is struck by how many of the names on them are Irish: Ahearns, Boyles, Farrellys, Quinns.

According to a tracker created by researchers at the University of Notre Dame, at least 19 countries have Sept. 11 memorials, including Brazil, Italy, and New Zealand. But it could be said that the small Irish town of Kinsale is home to two. Down the hill from the garden, in the center of town, is a white stucco hotel called The White House. Its manager, Michael Frawley, and his family maintain a display — filling one wall of the bar and spilling into the hallway — dedicated to those who died on Sept. 11.

Frawley’s parents visited their cousin, a firefighter in New York, a year after the attacks, and he gave them the jacket he wore that day as he tried to rescue people from ground zero.

When they returned to Kinsale, they hung the jacket in the hotel’s bar. Soon, visitors began handing over their own keepsakes: patches, badges, pins, hats, newspaper clippings — and pictures.

“When you look at this random town in Ireland that has not one, but two memorials to Sept. 11, it is kind of bonkers,’’ Frawley, 43, said. “But it’s nice, to have something that isn’t in Manhattan. It shows that Sept. 11 affected the whole world.’’

John Sullivan, 56, a retired firefighter who was at ground zero that day, said that he and his brother Stephen, 57, grew up in Queens playing Gaelic football and attending the local “feis,’’ or Irish dance festival. Their parents were both from County Kerry.

While John and Stephen, who is now a deputy chief with the Fire Department, have both visited the garden over the years, last summer they finally went together. “I first saw it when it was saplings,’’ John Sullivan said. “The growth is amazing. It’s life, you know?’’

John Sullivan estimated he knew at least 30 of the names on the trees at Ringfinnan. His brother knew as many, if not more.

But the garden in Kinsale may never hold more meaning for anyone than it does for John Murphy, who lives next door. When he stands in the quiet beneath the trees he remembers his aunt, who called every weekend while he was growing up to talk to him and his five siblings for at least 45 minutes each.

Kathleen Murphy had 29 nieces and nephews, he said, but she knew details about all of their lives — whom they were dating, which subject in school was giving them trouble.

John Sullivan said that when he is up on that hilltop in Cork, with a view of endless greenery and distant mountains far away from downtown Manhattan, he can feel something he couldn’t even consider on Sept. 11, 2001: peace. He once tried to visit the museum and memorial at ground zero, but he said he had to leave. “It was too emotional. I didn’t find it peaceful. It gets in your head again,’’ Sullivan said. “But I don’t feel that when I go to the trees.’’