New York, said Nathan Glazer and Daniel Moynihan in their classic book “Beyond the Melting Pot” (1963), was once an Irish city. It’s not an exaggeration. In 1855, 28% of New York residents were Irish-born. In that year, St. Peter’s Church, on Barclay and Church streets, was 15 years old — though the parish was 75 years old. That makes it the oldest Roman Catholic parish in the state.

The parish dates from 1784. For the century or so between England’s Glorious Revolution and the end of the American Revolution, the practice of the Roman Catholic faith was expressly forbidden in New York. The new nation offered the unbeatable combination of religious freedom and economic opportunity. And the Irish came.

At first, the Irish experienced wretched conditions in New York. Having been subsistence farmers back in Ireland, the newcomers seemed to possess no urban skills. In short order, however, they drew upon centuries of experience in underground organizing, as well as their verbal skills, to gain a foothold in, and eventually control over, hierarchical organizations of various kinds. These included the local Church (to this day every archbishop of New York has been of Irish extraction), the Democratic Party, and the police department.

No building, not even the two cathedrals called St. Patrick’s, puts one more in mind of the New York Irish than St. Peter’s. At least not since September 11, 2001. After that day, the Irish heritage of New York flooded back into our consciousness, as we scanned the newspapers’ lists of fallen firefighters and police, and saw — were surprised to see — how many of the surnames were Irish.

When fire department chaplain Father Mychal Judge died at the World Trade Center, firefighters carried his body to St. Peter’s, only one block from the northern edge of ground zero. They placed Father Judge’s body upon St. Peter’s altar, knelt and said a prayer, then returned to the scene of devastation. That the beloved Father Judge’s parents were Irish immigrants, and that St. Peter’s was the city’s oldest Catholic parish, seemed somehow, heart-breakingly, apt.

The church building is one of our finest survivors of the Greek Revival period. While Greenwich Village and Brooklyn Heights possess countless Greek Revival row houses, it’s buildings like St. Peter’s, with a full temple front, that come to mind when we think “Greek Revival.” A broad flight of stairs leads from Barclay Street to a portico marked by six massive freestanding Ionic columns of granite. The roof they hold up carries a triangular pediment. Most of our Greek Revival pediments are bare, like picture frames without a picture. Here, the pediment is almost bare, save for a central niche bearing a figure of St. Peter. The granite wall along Church Street is an austere composition of rectangular aisle windows and square clerestory windows. The sumptuousness of the interior belies the austerity of the exterior.

St. Peter’s acquired this site in 1785 from Trinity Church. Church Street is named for Trinity Church, and Barclay Street is named after Rev. Henry Barclay, the 18th-century rector of Trinity Church.

Many people visit ground zero on St. Patrick’s Day. They should not neglect to visit St. Peter’s Church as well.

fmorrone@nysun.com