The church at 16th and I streets in downtown DC does not match the usual images of a visually appealing house of worship. It bears no resemblance to the picturesque churches of New England with their white clapboard and soaring steeples. And it has none of the robust stonework and stained-glass windows of a Gothic cathedral.

The Third Church of Christ, Scientist, is modern architecture. Octagonal in shape, its walls rise 60 feet in roughcast concrete with only a couple of windows and a cantilevered carillon interrupting the gray façade. Surrounded by an empty plaza, it leaves the impression of a supersized piece of abstract sculpture.

The church sits on a prime tract of land just north of the White House. The site is so valuable that a Washington-based real-estate company, ICG Properties, which owns an office building next door, has bought the land under the church and an adjacent building originally owned by the Christian Science home church in Boston. It hopes to cut a deal with the local church to tear down its sanctuary and fill the assembled site with a large office complex. The congregation, which consists of only a few dozen members, is eager to make the deal—hoping to occupy a new church inside the complex.

DC’s Historic Preservation Review Board has refused to permit the church’s demolition, designating it a historic landmark in December 2007 and then issuing an order that it must remain standing. The 38-year-old church was nominated for landmark status by the city’s leading preservation groups, the DC Preservation League and the Committee of 100 on the Federal City, which consider it an outstanding example of Brutalism, an architectural style that gained popularity in the 1950s and ’60s. The architect, Araldo Cossuta, was a partner of I.M. Pei.

While some architects favor saving the church, there is outrage among members of the congregation, who have a list complaints about the building’s shortcomings. The fortresslike exterior, paucity of windows, and smallish entrance suggest a World War II bunker that does not convey a welcoming spirit. Heating and cooling costs are high, the concrete is cracking, the roof leaks, and the building needs millions of dollars of renovation.

A political and legal battle has developed, and new players have jumped into the fray, raising questions about architectural quality and the city’s power over historic properties as well as religious liberty and property rights. Mayor Adrian Fenty has signaled his preference for replacing the church with a tax-generating office building, and Councilman Jack Evans has introduced legislation to allow demolition by exempting the church from the city’s historic-preservation law. A Washington-based foundation dedicated to protecting the free exercise of religion is supporting the congregation, and the National Trust for Historic Preservation wants the church saved.

DC’s planning director, Harriet Tregoning, has held a hearing to consider the church’s appeal of the Historic Preservation Review Board’s denial of a demolition permit, and her decision is expected soon. Whatever her ruling, the losing side seems likely to head to court, where the dispute would shape up as a test case of national importance.

The conflict over the church has brought to the fore a broader issue that will be played out in Washington over the next decade: Of the thousands of modernist buildings built from the 1940s through the 1970s, which ones have the architectural distinction or other significance to merit protection? Are some of these structures, often not that attractive or lovable, worth saving as a reminder of their time? Are works by I.M. Pei, Edward Durell Stone, or Chloethiel Woodard Smith as important as the work of John Russell Pope or Adolf Cluss? Is Brutalism worthy of the same respect as Beaux Arts?

No tears will be shed by anyone about the demolition of many of Washington’s postwar office buildings. No one is objecting as the boring boxes in downtown DC and Rosslyn are gutted and rebuilt or flattened and replaced. No one rushed to the picket line to protect DC’s old convention center or the Capital Centre, home of the old Bullets and Capitals.

Donovan Rypkema, a Washington real-estate consultant with experience in preservation issues, puts it this way: “Mediocre judges don’t belong on the Supreme Court, and mediocre buildings don’t deserve historic designation. . . . The vast majority of what has been built in America in the last 50 years is crap.”

A few of DC’s modern buildings already have been protected with landmark status, the first being Arena Stage in 1980, which was designed by Harry Weese, the architect who also designed Metro’s subway stations. Other newly designated landmarks include the Watergate and the Washington Hilton as well as works by Ludwig Mies Van Der Rohe (Martin Luther King Jr. library), Marcel Breuer (Department of Housing and Urban Development), and Victor Lundy (US Tax Court). Others are so admired that they seem certain to join the protected list—from Philip Johnson’s pre-Columbian museum at Dumbarton Oaks to the East Building of the National Gallery of Art by I.M. Pei.

The dilemma will arise on the buildings between the iconic and the crappy, buildings that may be judged important by architects or historians but ordinary or ugly by nonexperts. Most of these structures are approaching middle age—50 years is the customary point when they are first up for historic designation—and they house some well-known government agencies and private institutions.