The New York architects whose names the public knows best aren’t necessarily the ones who created the world in which most New Yorkers live.

Emery Roth & Sons, for example, designed or helped to design one half of all the office space constructed in New York City between 1950 and 1970. William Higginson designed more of the city’s reinforced-concrete factories and warehouses than did any other architect. Herman Jessor may have designed more housing units than any other architect. Theatergoers may not know how well they know the architecture of Herbert J. Krapp. And for a New York Catholic, there’s a very strong chance he or she worships in a church designed by Patrick Charles Keely.

Keely came to Brooklyn in 1841 from Kilkenny, Ireland, and for the next 55 years developed a practice that, in the words of the architectural historian William Pierson, “became a virtual monopoly in Catholic church building.”

No one knows how many churches Keely designed, but estimates range from 500 to 700 throughout North America. He designed a few non-Catholic churches, like Brooklyn’s Episcopal Church of the Redeemer (1870) on Pacific Street at Fourth Avenue. And he designed a few non-Gothic churches , such as the marvelously Baroque St. Francis Xavier (1882) on 16th Street between Fifth and Sixth avenues in Manhattan. But Keely’s stock in trade was Catholic churches in the Gothic style. What’s remarkable is how good so many of them are. And how many architects designed so many buildings that hold so much special meaning in people’s lives.

A fine small exhibition in the innovative Public Perspectives Exhibition Series in the Brooklyn Historical Society’s Independence Community Gallery, “Sacred Hearts: A Journey of Italian Catholics in the Borough of Churches” prompted my thoughts on Keely. The series invites Brooklyn residents to submit proposals for exhibitions on aspects of borough history. Exhibitions are then developed with the aid of the society’s professional staff. “Sacred Hearts” comes from John Heyer, a parishioner of Sacred Hearts of Jesus and Mary and St. Stephen’s Church, on Summit Street at Hicks Street in Carroll Gardens. The unwieldy name, like that of so many Catholic churches, reminds us of the mergers of parishes that have taken place over the years. This year marks the 125th anniversary of Sacred Hearts parish, which merged with St. Stephen’s and moved into its present 1860s building in 1941, after Robert Moses condemned Sacred Hearts of Jesus and Mary Church, at the intersection of Degraw and Hicks streets, to make way for the Brooklyn-Queens Expressway (which, as it happens, roars in a trench right alongside the present edifice).

The exhibition tells the story of Brooklyn’s oldest Italian Catholic congregation, formed in 1882, when Italians had begun to migrate in noticeable numbers to New York — a migration that would soon become a flood. In 1889, Mother Frances Xavier Cabrini (canonized in 1946) came from Italy to minister to New York’s increasing Italian flock, and three years later went to Sacred Hearts in Brooklyn, where she established the parish school. (Mother Cabrini Park, on President and Van Brunt streets, sits on the site of the original Sacred Hearts Church, built in 1882.) A new Sacred Hearts Church rose in 1907, reflecting the stunning growth in Brooklyn Italians. According to the Brooklyn Eagle, around that time, Sacred Hearts served the largest Italian community in America.

As Mr. Heyer tells us in his exhibition, Irish dominated the New York church at the time of the Italian migrations, and Italians felt more comfortable forming their own parishes, with Italian clergy, and Romanesque architecture in contrast to the prevailing Gothic of the Irish. Italians (like the Irish before them) worked the Brooklyn docks and dominated Red Hook, where today some old Italian businesses hang on, such as Defonte’s Sandwich Shop (Columbia and Luquer streets) and Ferdinando’s Focacceria (Union and Hicks streets). Today we don’t think of Red Hook as very Italian, but we think of adjacent Carroll Gardens as Italian, indeed. I put that in quotes because a lot of the Italian old-timers don’t say “Carroll Gardens,” a realtors’ coinage of the 1960s. It’s still “South Brooklyn” or, I’ve heard said, part of Red Hook. The construction of the BQE forced many of the waterfront Italians inland, as when Sacred Hearts came to share space with St. Stephen’s, originally an Irish church.

When I look at a church like Sacred Hearts and St. Stephen’s I see not an assembly-line production but a work of real beauty. Gothic forms themselves, and Keely’s handling of them (which owed muchtotheEnglishgeniusA.W.N. Pugin, who decorated the Houses of Parliament), possess an inherent generosity of spirit. They embody and enshrine the memories of countless extraordinary and ordinary lives, and sing them back to us when we pass by.

(“Sacred Hearts” is at the Brooklyn Historical Society, 128 Pierrepont St. at Clinton Street, through December 30.)