A phenomenon of Mass mobs, where large groups of suburbanites worship in the city on a given Sunday, is shining new light for a day on urban parishes that are dwindling or, in some cases, have been closed.
Generations of immigrants sacrificed to construct many of these magnificent buildings. Often, they rose within a couple of blocks of each other to meet the language and cultural needs of the European immigrant communities.
The nostalgia for these churches is understandable. However, their fate may offer more contemporary lessons for religious groups in a diverse culture.
Today, many of those Polish Catholic or Italian Catholic or German Catholic churches in cities such as Cleveland and Buffalo have been closed or merged as succeeding generations have moved away. Many of their children no longer see the need to merge their religious and ethnic identities.
And many of the congregations failed to integrate their new neighbors -- white, black or Hispanic -- into their parishes.
The Catholic Church is trying to address those issues as it deals with new generations of immigrants from Latin America and the Caribbean seeking a familiar spiritual home in the U.S.
The church has greatly increased the number of Hispanic ministries and Spanish-language Masses. But in contrast to the response to earlier waves of European immigrants, congregations also are making efforts to integrate the newest immigrants within larger parish communities.
The difficult task parishes face is to meet the special needs of recent immigrants without dividing congregations into ethnic enclaves.
The challenge of serving ethnic ministries may be even greater for Eastern Orthodox churches. Many have been less willing to give up the ethnic nature of their congregations even as fewer and fewer in succeeding generations speak the native language of their ancestors and most marry American spouses outside their tradition.
A survey of major Eastern Orthodox churches in the United States found just two-thirds of the liturgy is in English on average in the large Greek Orthodox Archdiocese of America. The percentage drops to around half for U.S. congregations that are part of the Ukrainian Orthodox Church or the Serbian Orthodox Church.
And language appears to matter, according to researcher Alexei Krindatch.
One third of the parishes where English was used more than 90 percent of the time reported 60 percent of their parishioners attended services weekly, he found in a 2011 survey. Only 15 percent of such English-speaking churches reported attendance rates below 30 percent.
In contrast, half of the parishes where English was used less than 90 percent of the time reported fewer than three in 10 members were regular attenders.
Hispanics now make up nearly 40 percent of an estimated 78 million U.S. Catholics. And the demand for targeted ministries is growing.
Some 4,500 congregations, about a quarter of U.S. Catholic parishes, "intentionally serve" Hispanic or Latino Catholic communities.
About 6 percent of all Masses in the United States are celebrated in Spanish, according to the 2012-2013 National Study of Catholic Parishes with Hispanic Ministry. The study was led by Boston College researcher Hosffman Ospino in collaboration with the Center for Applied Research in the Apostolate at Georgetown University.
Spanish-speaking ministries are particularly important for new immigrants, "who often rely on parishes to remain connected to their religious roots and identity while they integrate into the larger society. Parishes matter," Ospino reported.
Some concerns are on the horizon, however.
For one, many Spanish-speaking priests trained in Hispanic ministry following the Second Vatican Council in the 1960s are reaching retirement age. Fifty-nine percent of pastors in parishes with Hispanic ministry are older than 55, and vocations are not keeping pace with church growth.
For another, the study finds, pastoral leaders report many Hispanic Catholics are being only "minimally integrated" into the life of the larger parish community.
"Parishes must engage in serious discernment with all their members, Hispanic and non-Hispanic, about building communities where all members find themselves at home," Ospino said.
Whose parish is it anyway?
Orthodox churches that have been slow to embrace congregational diversity know there are consequences.
In the 2007-2008 Orthodox Church Today study, four in five parishioners said one of the most urgent concerns facing their congregations is the issue of youth and young adults leaving the church.
Some Orthodox jurisdictions such as the Antiochian Archdiocese and the Orthodox Church in America use English almost exclusively in services. But many congregations still place a premium on their ethnic heritage.
For example, in the 2011 survey, more than eight in 10 parishes in the Serbian Orthodox Church and two-thirds of congregations in the Greek Orthodox Archdiocese reported, "Our parish has a strong ethnic culture and identity that we are trying to preserve."
As with less use of the English language, congregations with a strong emphasis on their ethnic heritage had on average dramatically lower rates of church attendance.
"The high rates of attendance in American Orthodox parishes are typically associated with high usage of English in worship services and with churches which do not emphasize their ethnic identity and heritage," Krindatch concluded.
The apparent takeaway? Developing vibrant parish communities as the ethnic and social makeup of congregations and communities evolve requires planning and a willingness to be more inclusive.
Get enough people together for one day, and nostalgia can be revived in a flash. Hold on too long to the past, however, and no mob may be able to save a congregation.