About 500 feet northeast of this site, St. Nicholas Church was located in an area that was once the heart of a large Croatian community called Mala Jaska.
Croatian immigrants began settling in Allegheny City (now Pittsburgh's North Side) in the late nineteenth century, after their government deprived its citizens of political power, agricultural markets, and land ownership. Many of the immigrants were farmers from the Jaska region, where the economy was particularly hard hit by the ruination of its vineyards. Nearly all the worker immigrants were unskilled men, and one third were illiterate. The displaced Croats hoped to earn enough money in America that they might one day return to their homeland. In the spirit of non-permanence, most of the Croatian immigrants rented their living quarters, sometimes living in boarding houses with as many as dozen other working men.
In 1894, the increasing number of Croatian immigrants in Allegheny City formed St. Nicholas Roman Catholic Parish, which was the first Croatian national parish in the United States. Named for the patron saint of Jaska, the parish held church services in a house until a larger building could be obtained.
It was not long before the parish outgrew its small building, necessitating the construction of a larger edifice. Divided over where the new church ought to be constructed, the parish split and built two churches in 1900-1901 - one in Allegheny City and the other in Millvale.
The Allegheny City (North Side) congregation also built a rectory immediately west of the church in (1900-1901). In 1931, the parish purchased the local public school (located immediately east of the church and pictured right) and converted it to an eight-grade parochial school.
A convent was built in 1950 to house the sisters who taught at the school. An elaborate hillside grotto, dedicated to Our Lady of Lourdes, was developed in 1944 between the church and the rectory.
In 1994, the Diocese of Pittsburgh merged the St. Nicholas, North Side and St. Nicholas, Millvale parishes. The East Ohio Street building remained in use until 2004 and was razed in 2013.