Boats are shown off Castine in 2015. Credit: Ashley L. Conti

When he stepped inside the Pantheon during a trip to Rome in the early 1950s, William J. Murtagh began to reconsider all he had been taught. He had just graduated from the University of Pennsylvania with an architecture degree, but his studies were almost entirely concentrated on the austere Bauhaus school of 20th-century design.

“I stood there most of the day wondering what was wrong with the past five years of my life,” Murtagh later recalled, “because you couldn’t call this a bad building.”

On his return to the United States, he immersed himself in the field of historic preservation, taking up the banner of a budding campaign to save the country’s colonial farmhouses, Civil War battlefields, Victorian mansions and Old West saloons from the crush of development.

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As entire city blocks were razed in urban renewal projects, interstate highways were paved across the countryside and architectural marvels such as New York’s original Penn Station were demolished to make way for bigger, newer structures, Murtagh helped lead a growing resistance effort that culminated in the passage of the National Historic Preservation Act of 1966.

In its aftermath, he was appointed the first “keeper” of the National Register of Historic Places — a job that made him the curator of the nation’s now-sprawling catalogue of significant districts, objects, buildings, sites and structures.

Murtagh, who was described in a 2005 presidential citation from the American Institute of Architects as “the beloved pied piper of preservation” and a champion of “the continually nourishing presence of the past,” was 95 when he died Oct. 28 at a retirement community in Sarasota, Florida.

The cause was complications from congestive heart failure, his nephew Dean F. Murtagh said.

In a more than half-century career, Murtagh served as a vice president at the National Trust for Historic Preservation; helped establish preservation programs as a professor at Columbia University, the University of Maryland and the University of Hawaii; and wrote what is widely considered the first major textbook in his field, “Keeping Time: The History and Theory of Preservation in America,” originally published in 1988 and now in its third edition.

“Quite simply, historic preservation in America would not be what it is today without the vision, leadership, and extraordinary contributions of Dr. William J. Murtagh,” Stephanie Meeks, president and chief executive of the National Trust, said in a statement.

“In many ways,” she added, “Dr. Murtagh gave preservation in America itself a history. His thinking and scholarship informed the National Historic Preservation Act of 1966 . . . and, with a steady hand and a deep appreciation for international approaches to saving places, he continued to lead the preservation movement in more than five decades since.”

Murtagh was best known for his 13 years as keeper of the National Register, where beginning in 1967 he determined which sites would join a list that now numbers more than 92,000 individual properties and 1.4 million total entries. The designation qualifies sites for federal grants and tax provisions but does not entirely prevent properties from being destroyed or altered.

Instead, the register’s creation offered preservationists a new tool in the face of the bulldozer, mandating that federal projects affecting a registered site undergo a review from the Advisory Council on Historic Preservation, which may criticize but not altogether halt a project that is funded or licensed by the U.S. government.

“This is definitely a way to combat visual and cultural pollution, which can be as depressing as air and water pollution,” Murtagh told the New York Times in 1971. Indeed, the Times reported that after the French Quarter of New Orleans was listed in the register, the Transportation Department was persuaded to alter the route of a proposed elevated highway through the neighborhood.

Under the National Historic Preservation Act, which created the register, it was the responsibility of state preservation programs to submit potential historic sites for Murtagh to review. But as thousands of houses, districts and other miscellanea of the American landscape poured in, it became clear that Murtagh approached his job not so much as a judge or critic but as a cheerleader for local communities.

By all accounts, nearly every submission was accepted by Murtagh, so long as a state provided evidence that a place was somehow, to some degree, significant, no matter how provincial it might seem to outsiders. The criteria for historic significance was broad enough to encompass the cable cars of San Francisco, the first U.S. street to be paved with concrete (in Bellefontaine, Ohio), one of the first brooder houses for broiler chickens (in Georgetown, Delaware) and a prairie-style Frank Lloyd Wright home in Chicago.

“He set the tone for the register, demonstrating an openness to what people and communities around the nation value,” said Carol Shull, who worked alongside Murtagh and later served as the third official keeper of the register. “I think we all followed that precept, of not thinking that we were bureaucrats in Washington telling the people, ‘We don’t really value this; why’d you send this up here?’”

In frequent trips across the country to meet with state and local officials, Native American tribal leaders and everyday citizens, Murtagh resisted efforts to pin down exactly what deserved to be included in the register — or, on one occasion, exactly how many of Oregon’s 16 coastal lighthouses deserved to be nominated.

“Well, I’m not going to tell you. I don’t live in Oregon. I don’t see your lighthouses. How important are they to you as an Oregonian?” Murtagh was said to have replied, according to a 2010 article by Shull, published in Preservation magazine.

“If they’re not that important, don’t submit any of them. If only one of them is important, submit one. If you feel they’re all important, submit all of them,” he said. “How many do you think you need to keep Oregon’s sense of locality, and place, and identity?”

William John Murtagh was born in Philadelphia on May 2, 1923. His father owned butcher shops, and his mother was a homemaker.

Murtagh received a bachelor’s degree in architecture from the University of Pennsylvania in 1950, and worked under preservationist Charles E. Peterson to help develop Independence National Historical Park in Philadelphia.

Yet after an automobile accident kept him away from the drafting table for a year, he decided to return to graduate school at Penn, where he received a master’s degree in art history in 1953 and a doctorate in architectural history in 1963, while embarking on the European travels that ignited his interest in preservation.

His early focus was on Moravian architecture, studying the Colonial-era buildings built by German immigrants in cities such as Bethlehem, Pennsylvania, where he directed the Kemerer Museum of Decorative Arts and oversaw the organization Historic Bethlehem.

His work there attracted the attention of Richard Hubbard Howland, first president of the National Trust, a nonprofit organization that was founded by congressional charter in 1949 to acquire and preserve historic sites across the country.

Murtagh was hired as Howland’s assistant in 1958 and soon promoted to serve as the organization’s director of education and then of programs.

He also sat on a committee that produced “A Report on Principles and Guidelines for Historic Preservation in the United States,” a 1964 document credited with outlining the principles enshrined in the National Historic Preservation Act, and he was a founding member of the U.S. Committee of the International Council of Monuments and Sites.

After retiring from the National Register, Murtagh worked as a professor and returned for several years to the National Trust as vice president of preservation services. He received the organization’s highest honor, as well as the Interior Department’s Distinguished Service Award.

His marriage to Mary Louise Morton ended in divorce, and he leaves no immediate survivors.

At his request, Murtagh will be buried near his summer home in Penobscot, Maine. His ties to the area stretched back to the first grant he awarded as keeper of the National Register, which enabled the town of Castine to rescue a historic home, according to his friend Walter Smalling, a former photographer with the National Park Service.

When Murtagh visited Castine to examine the home, Smalling said, he fell in love with the town — “he said it was so quiet you could hear the ice melt in your martini” — and came across a 19th-century schoolhouse, the Abbott School building, that was going to be altered and turned into a garage.

To save the structure, Murtagh bought it, and then lived there for about 15 years before moving to a small home in Penobscot. The schoolhouse has since changed hands and now houses the Castine Historical Society. It is listed, naturally, on the National Register of Historic Places.