The City of Philadelphia was created in 1682 as part of William Penn’s “Holy Experiment” where people of different religious faiths could worship freely and live in peace.

Penn’s legacy of religious tolerance endures through the city’s vast diversity of religious buildings. A recent report by PennPraxis, the applied research arm of PennDesign, counted 839 historic sacred places in the city—temples, synagogues, mosques, and churches—that were built before 1965, or about one for every 1,900 residents. Most were constructed between 1865 and 1929, the age of Philadelphia’s largest population growth.

From 2011 to 2015, at least 23 of the city’s historic sacred places were demolished, primarily by developers.

Molly Lester, a research associate at PennPraxis, says there has been a sense in recent years among preservationist, urban planning, and social practice circles that a large number of historic sacred places in the city are being torn down, but there was no baseline to determine whether the loss of historical landmarks is an actual trend.

“Philadelphia’s Historic Sacred Places: Their Past, Present, and Future,” a report funded by Pew Charitable Trusts and led by PennPraxis, with assistance from Partners for Sacred Places, establishes this baseline for use by succeeding preservationists and researchers. The study aims to document Philadelphia’s historic sacred places, examine the role these institutions play in the city’s public life, and analyze the dynamics that will likely determine whether buildings currently functioning as houses of worship will continue to do so in the future.

“With this project, we wanted to establish the first baseline to compare against for any future efforts to monitor and advocate for the preservation of these places, and advocate for the constraints that the congregations are up against because this is an issue related to both the building, but also the people occupying the building, obviously,” says Lester, one of the study’s project managers. “We really wanted to understand what might be factoring into why congregations are leaving their buildings and the buildings are getting torn down.”

The report was structured around a field survey designed to produce an inventory of all the historic sacred places in the city that were built as sacred places, omitting locations like storefront churches, and school buildings and community centers where congregations meet. Researchers also conducted interviews with clergy and lay leaders from 22 congregations to better understand their decisions related to their buildings.

Lester says both external and internal factors are at play in the loss of historic sacred places. External factors include changing communities and neighborhoods.

“Sometimes, the fact that the neighborhood is changing means that the congregation members now live farther and farther away, and have to commute to church, or to synagogue, or to temple, and that commute is kind of a distancing factor,” Lester says.

Internal factors include aging and dwindling congregations, financial well-being, and the leadership abilities of clergy and other decision-makers.

In 2015 and early 2016, 83 percent of Philadelphia’s 839 historic sacred places remained in religious use, although nearly half were no longer occupied by the buildings’ original congregations. About 10 percent of historic sacred places had been adapted for other uses, such as housing, offices, and child care centers.

Lester, a preservation planner by background, says protecting the city’s historic sacred places is vital because they are important parts of the built environment.

“As physical buildings, these are places that represent, in some cases, architectural significance because they were designed by prominent architects,” she says. “Even if they’re not the high steeple churches that come to mind and they’re smaller, more community-based churches, or temples, or synagogues, or mosques, for those communities, they represent landmarks of the history of their faith and practicing in Philadelphia.”