NEW YORK, NY.- Lisa Tofano was baptized, confirmed and married at the Good Shepherd Lutheran Church on Lake Opeka in Des Plaines, Illinois. When she and her husband, John, visited the church last fall, however, it wasn’t to worship but rather to celebrate their 34th wedding anniversary at what the church had become: the Foxtail on the Lake, a restaurant.

The transformation was not easy: The shuttered church needed an 18-month, $6 million gut renovation, and a new 3,000-square-foot kitchen, before it could start offering items such as paella and beef shawarma, said David Villegas, a managing partner of Foxtail, who said he had been “a bit nervous” before the restaurant’s opening in November about the reaction of former parishioners. For Lisa Tofano, though, “a church is more about the people than the building,” she said.

Across the country, the number of empty churches and other houses of worship is sharply rising, and these structures, often unique architectural gems, have become huge draws for business owners.

Eileen Lindner, a sociologist and Presbyterian minister who is a former editor of the Yearbook of American & Canadian Churches, which analyzes census data on religious organizations and houses of worship, said that she expected as many as 100,000 Protestant church properties to close by 2030. That figure, which may come close to 20% of all existing Protestant churches, is a significant increase over the past decade, Lindner said.

The closings stem largely from a drop in church attendance during the COVID pandemic, and fewer people, especially younger adults, affiliated with religious organizations than in the past. The decline has been happening for decades. In the late 1940s, 76% of Americans said they belonged to a church, synagogue or mosque, but by 2020 that number had dropped to 47%, Gallup polling found.

The result is that congregations are closing or merging with others, leaving some capacious sanctuaries and outlying buildings underused or unused altogether. Many religious organizations are having to rethink how to make the best use of their largest assets — the buildings as well as the underlying land — and give them a second life.

Madeline Johnson, who oversees research at the University of Notre Dame on properties owned by the Catholic Church as well as other religious organizations, said not much is off limits for what a church could become. Of the many denominations, the Catholic Church might have the most stringent restrictions, Johnson said. The church stipulates that new uses “may be profane but not sordid.” But even that limitation affords a lot of leeway.

With their vaulted ceilings and stained glass windows, the architectural forms of churches have long attracted business owners, despite structural problems that can add significantly to renovation costs.

When a product design consulting firm, Argodesign, outgrew its offices in Austin, Texas, its founders were deliberate in their search for a new space. They saw potential in an abandoned 1930s-era church with a “rose window,” a round shape often found in churches, near the city’s bustling downtown South Congress area. The structure could accommodate up to 70 employees and had a parking space for a car the team had constructed together, said Sonia Prusaitis, the general manager of the office. The firm moved into the property in 2022.

Around the world, houses of worship have been converted to restaurants, breweries, hotels, art centers, theaters and even sports complexes. Some abandoned churches have been transformed into mixed-use developments, blending retail and residential space, and affordable housing.

In 1983, the Gothic revival Episcopal Church of the Holy Communion in New York City was converted into a disco called the Limelight, known for its sometimes drug-fueled party scene. The structure has since gone through several iterations, including a shopping mall, a gym and a market. In St. Louis, an abandoned church became an indoor skatepark called Sk8 Liborius. (It burned down last year.) And a branch of the Black Art Library in Detroit opened this year in a repurposed church.

The process of transforming something old into something new can hit a number of bumps along the way. New structures may need zoning changes, such as when a church is in a residential neighborhood that doesn’t otherwise permit commercial uses. For instance, Foxtail, the restaurant in Des Plaines, Illinois, needed a zoning variance to sell alcohol.

A new business sometimes needs city, state or federal approval before alterations can take place if the church is a landmark structure or in a historic neighborhood. Churches are often deconsecrated before the buildings even hit the market.

“One of the great difficulties in repurposing a church is that it’s a pretty specific type of space,” said Ari S. Heckman, a co-founder and the CEO of the Ash hotel group, which turned a once grand old church in New Orleans into the Hotel Peter and Paul. The space has an eclectic style that merges religious vestiges with modern amenities.

“It’s hard to subdivide in a way that makes sense for a lot of uses, which may be why the original developer couldn’t make it work,” he said.

Some renovation challenges are readily apparent, but others are known only once the layers of Sheetrock or plaster are peeled back. That can reveal a weak infrastructure that is out of date and, most likely, out of code, said Jay Colombo, an architect at the Michael Hsu Office of Architecture in Austin who recently worked on converting an old church into a new outpost of Loro, an Asian barbecue restaurant, in Houston. “Even the studs can be rotted away,” he said.

Additionally, energy-efficient heating and air conditioning, updated electrical wiring, new plumbing, and internet accessibility must all be installed. Mold or asbestos might be found as well. And fire codes for commercial businesses require sprinkler systems, which proved especially problematic at the church in Des Plaines, said Villegas, the managing partner of the new restaurant there, because of the soaring roofline of the A-frame building, typical of midcentury-era churches.

Although the costs of adaptive reuse — the renovating of existing buildings for new uses — can eclipse new construction, the renovation can sometimes be done more quickly since there’s no outside structure to build. And the construction is considered more sustainable since the bricks, concrete and other materials are generally repurposed rather than ending up in a landfill. But old wiring and plumbing, and sometimes roofing, may not be salvageable.

Most who choose to renovate try to retain some reference or vestige of the church that the building once housed. Argodesign, the firm in Austin, preserved the shape of the rose window in its new office space and replaced it with energy-efficient glass, said Micah Land, an architect with Michael Hsu, who worked on the project. Foxtail incorporated the former church’s massive stained-glass windows and cross into the design for the new restaurant, and it keeps a piece of the altar near the entrance.

At the Hotel Peter and Paul in New Orleans, the former church’s convent, rectory and school were transformed into guest rooms. The sanctuary is now an open space for events.

“We didn’t alter the historic fabric of the church itself all that much,” said Heckman, whose hotel group handled the renovation. The hotel kept side altars, stained glass and original light fixtures, adding character to the venue, which is used for bar mitzvahs, weddings and corporate events. “To the degree churches don’t serve their original religious purpose, I think they still play an important role as places for celebration,” he said.

Renovations transform religious buildings in another fundamental way that is consistent with contemporary design. Typically, a church “is very insular — it’s all about the inside and how it works,” Land said. The challenge is to “flip that notion of insularity and open the structure to the street.” That’s what Villegas sought at Foxtail as well, where a solid brick wall was opened to create a view of the nearby lake.

It’s a development that Tofano, the former parishioner, likes. “It’s beautiful,” she said. “I wish the church I now go to had the budget.”

This article originally appeared in The New York Times.