Dwindling congregations and aging buildings have left these buildings empty until now.
There has been a spate renovations in the last couple years, but don't expect the places of worship to open back to churchgoers.
People once filled the pews at St. Joseph's Catholic Church in San Francisco's South of Market neighborhood.
"I know people who grew up here and got married in this church; I know people who were buried in this church," developer Brian Speirs said.
Today St. Joseph's is empty, stripped of its sacred shrines, now just another big, empty San Francisco church in need of a new life.
"I thought it was so amazing, but sad that it had not been touched in 25 years," Chris Foley said.
Foley bought the nearly 100-year-old building three years ago. He is working with Speirs to remake the historic landmark. St. Joseph's was closed after the 1989 Loma Prieta earthquake because it didn't meet seismic standards.
"What we realized was, with technology companies in mid market being so hot, they are very interested in creative space, so what we decided to do is we got it approved as an office building," Foley said.
The plans call for 22,000 square feet of office space and a restaurant. The exterior will be restored and the building will be brought up to modern codes.
Cost is most often what keeps churches from being restored.
"To rehabilitate a building like this is about $17-$19 million dollars," Foley said.
St. Joseph's is just one of a number of church buildings around the city preservationists hope can be saved.
"The adaption of a building like that, that removes it from the vacant list, that creates activity around and within a community, a neighborhood is far more valuable than seeing a building vacant," San Francisco Historic Preservation Commission spokesperson Charles Chase said.
The Second Church of Christ Scientist on Dolores Street was built in 1915. It is an important architectural landmark in San Francisco.
"This is one of two wood framed truss system domes in San Francisco," owner Siamak Akhavan said.
Akhavan is planning to turn the ornate church into four residential units.
"There's going to be three multilevel units on the ground floor and one loft unit up here in this dome," he said.
Neighbors fought to keep the building from being torn down.
"We'd prefer that the building stayed as a church, but unfortunately the congregation got smaller and smaller and they couldn't afford to maintain the building, so they had no choice but to sell the building," Mission Dolores Neighborhood Association spokesperson Peter Lewis said.
Neighbors support the plan to convert the church into homes. They already knew Akhavan could do it. Less than a block away, he restored another church, turning it into a multi-million dollar home.
"He put in a beautiful kitchen and when we turn this into classrooms, we'll keep the kitchen," Children's Day School spokesperson Molly Huffman said.
When the property didn't sell as a home the private Children's Day School bought it to convert into a middle school for 180 students.
The castle like architecture will remain untouched.
"The Tudor Gothic Hogwarts ambiance of the building is wonderful for middle school students," Huffman said.
Some neighbors protested elements of the school's plan, but finally reached an agreement.
Others are happy to see the school move into the empty corner.
"In San Francisco, I'd say that the majority of the churches are probably worth saving; there is a tremendous amount of outstanding church architecture in San Francisco," Lewis said.
But should every old church be saved?
That's the question being asked at St. John's United Methodist Church on Larkin Street. It is falling apart. What hasn't rotted has been vandalized.
"Three, four, five structural engineers who have said it's unsafe," developer John McInerney said.
The church closed nine years when the congregation shrank to about a dozen people. They could not afford the $6 million in repairs, so the church turned to McInerney. Together they want to tear it down and build 27 units of housing.
But the city is making it tough -- last month, officials rejected the plan saying it would "result in the demolition of an historic resource."
"Churches, religious institutions have a right to use and dispose of their property under both state and federal law," McInerney said.
The church is appealing the decision.