The D.C. Preservation League, originally named Don’t Tear It Down, has helped save from the wrecking ball countless historic structures in the nation’s capital. Now marking its 40th anniversary, DCPL has been relentlessly zealous. But it has done much to sensitize Washington’s residents, businesses and government officials to the value of preserving the city’s architectural landmarks and design heritage.

Such sensitivity had to be learned, because a few decades ago Washingtonians were not so attuned to preservation. In the 1950s and ’60s, the ethos and culture of planning, architecture, and urban development and redevelopment differed greatly from that of today. In architecture schools in the 1960s, no one talked about “historic preservation.” The country was preoccupied with slum clearance and urban renewal, with an emphasis on “new.” Designers and their clients looked to the future, not the past. Invention and innovation, not restoration and preservation, were the goals.

Attitudes began to shift in the 1960s as notable American buildings were being routinely knocked down, most famously New York City’s magnificent Pennsylvania Station, designed by McKim, Mead & White and built in 1910. Entire city neighborhoods, including much of Southwest D.C., were being razed. Some realized that if demolition continued unchecked, the day would come when the nation’s architectural legacy could disappear and be forgotten. People also perceived that much newly built, International-style architecture in the 1950s and 1960s was less than aesthetically lovable, especially in contrast to what wrecking balls were demolishing.

The prospect of a wrecking ball catalyzed the creation of Don’t Tear It Down, first established to oppose the planned demolition in 1971 of Washington’s Old Post Office building on Pennsylvania Avenue NW, designed in the late 19th century by Willoughby J. Edbrooke. Federal officialdom considered the Romanesque-style stone edifice functionally obsolete and saw it as an anachronistic impediment to completion of the neoclassically styled Federal Triangle, designed and constructed in the 1920s and 1930s.

Don’t Tear It Down mobilized preservation-minded volunteers and, during the nation’s second annual Earth Week, in April 1971, a march culminated in a rally at the Old Post Office building and garnered substantial publicity. Ensuing hearings on Capitol Hill, plus persistent advocacy by preservationists, ultimately persuaded the federal government to save the building. Subsequently, during those formative years of the preservation movement, Don’t Tear It Down helped save other buildings such as the Willard Hotel and the Franklin School.

In the early 1970s, if zealous preservation advocacy wasn’t sufficient, litigation was an option, if only to buy time. But litigation was costly. Instead, under D.C. law then in effect, nominating and obtaining designation of structures as historic landmarks could buy time, but keeping the wrecking ball at bay remained a challenge, especially in the face of new, economically beneficial real estate development.

In 1978, after Don’t Tear It Down pushed for stronger legislation, the District passed the Historic Landmark and Historic District Protection Act. Mandating an official listing of historic D.C. properties, it offered much better protection for landmarked structures through a time-consuming permit process and also public hearings. However, historic landmarking was not automatic. Nomination for landmark status required thorough documentation demonstrating that a property was historic, which depended on architectural or technological significance, significance of its architect or its significance in American history.

National attitudes about preservation were changing, too. Congress recognized that financial incentives could lessen resistance to preserving historic architecture and motivate property owners and developers to keep historic buildings. Consequently, federal tax laws were enacted to provide income-sheltering tax credits and write-offs if property owners and developers invested money in rehabilitating landmarked structures. The tax incentives proved reasonably effective.

Don’t Tear It Down became the D.C. Preservation League in 1984 and substantially expanded its aspirations and scope of activities. Since then, in addition to efforts aimed at preserving threatened architectural monuments in the heart of the District, DCPL has focused on historic buildings throughout the city. Committed to educational outreach, DCPL has sponsored preservation lectures, conferences, exhibitions and tours. It continually lobbies the D.C. government concerning preservation matters.

Both in Washington and throughout the country, the historic preservation movement has matured since 1971. No longer a grass-roots effort, it is an integral part of public policy at all levels. Adaptive reuse of old buildings, often combined with new construction, has become a common real estate development strategy, and often an indispensable component of economic-revitalization projects. It is likewise a beneficial sustainability strategy. Recycling an existing building conserves large amounts of embedded energy, labor and materials invested in the building when it was built.

Of course, not every old building is historic, and not every old building is worth saving. But most old buildings at least deserve due consideration before being torn down or radically altered, and that continues to be DCPL’s mission.

Roger K. Lewis is a n architect and a professor emeritus of architecture at the University of Maryland.