HAVERFORD, Pa. (AP) ?EUR??,,?(R) Party guests dancing before the ballroom's picture window at the Dolobran estate once glimpsed 150 acres of verdant, open countryside. Today, the gardener's quarters and farmhouse set downhill from the mansion are fenced off as individual properties. To keep just four original acres from further development, the current owner Amy Nislow had to buy a neighboring piece of land. Like many opulent Main Line estates that once sprawled west of Philadelphia, the estate built by Clement Griscom, an owner of the Titanic, has been subdivided. And, as with many Main Line estates, what's harder to find is the land that once surrounded them. "You might find the original house still there but the 100 acres around it are long gone,'' said Mike Weilbacher, executive director of the Lower Merion Conservancy, a preservation society. A handful of the estates remain intact, including Ardrossan, the 400-acre Villanova estate of the late Hope Montgomery Scott, on whom Katharine Hepburn modeled her Tracy Lord character in the 1940 film ``The Philadelphia Story.'' Only a few are open to the public. Chanticleer, the country home of chemist Adolph Rosengarten Sr., and Longwood Gardens in Kennett Square, a du Pont estate, survive as formal gardens open throughout the year. The majority, however, were carved up and the stately turn-of-the-century homes designed by architects Frank Furness, Wilson Eyre and Horace Trumbauer are now surrounded by modern housing developments. Designed as private resorts, complete with gentlemen's smoking rooms and women's parlors, the mansions went up in the boom years between 1890 and 1920, funded by the region's railroad and textile industries. The Main Line, and the wealth it came to represent, was named for the Main Line of Public Works, a train line extending west from Philadelphia that still ferries commuters to and from the suburbs. "The Main Line as a great place to live was brought about because of the Pennsylvania Railroad. At the same time, because the railroad was so successful, suddenly everyone wanted to live here, and that fueled a rush for land that prompted the breaking up of the big estates,'' Weilbacher said. After World War II, many families found the mansions, averaging between 15,000 and 20,000 square feet, and the large staffs required to maintain them too expensive. Houses not razed or bought by individuals became schools, offices, colleges or retirement communities, often with a fraction of the original acreage. Depending on how much land remains, the homes are worth $5 million to $8 million, said John Groff, executive director of Wyck, a Philadelphia Quaker landmark. "In the 1950s, these houses were really white elephants and could cost, after adjusting for inflation, $75,000 because nobody wanted them,'' Groff said. Market forces tend to value the mansions much less than the acres they occupy. Any preservation is largely left to homeowners. Even as historical landmarks, without municipal codes requiring preservation, the mansions can still be demolished. "What seems best able to survive is the one that can sit on 3 to 5 acres and adapt to what the lawyers and stockbrokers of today want, not to what the lawyers and stockbrokers of the early 20th century wanted,'' said Jim Garrison, a preservation architect for Hillier, an architectural firm in Philadelphia. ``It takes a special kind of customer to want one of those kind of buildings. They want less architecture and more gizmos.'' The Preservation Society of Newport County in Rhode Island found opening its famous mansions as public museums was the best way to raise interest in their preservation. The mansions date from pre-colonial days to the 1890s. The society currently owns 11 properties totaling 82 acres, chief executive Trudy Coxe said. Similar estates on Long Island ?EUR??,,?(R) some as large as 40,000 square feet ?EUR??,,?(R) are protected by New York's State Environmental Quality Review Act, which considers historical structures part of the environment. "In the development process, if you plan to subdivide an estate, you have to satisfy the agency and include possible impacts to historic resources. You have to plan for their preservation,'' said Charla Bolton, preservation advocate for the Society for the Preservation of Long Island Antiquities. On the Main Line, other than societies such as the Lower Merion Conservancy, there has been no major effort to document or preserve the estates. The mansions, whose residential settings are not well-suited to tourism, seem to survive best when privately owned. Donating the development rights, which protects property from future subdivision, offers homeowners tax advantages for preservation. "The intent is not just to preserve a building, but also the settings and some sense of how the Main Line used to be. You want to make sure of all traces of what was key to the development of the region are preserved as living organisms, not museum pieces,'' Garrison said. The estates still require extensive care. Along with other home improvement projects, Nislow has spent tens of thousands of dollars on Dolobran's ballroom alone, repairing years of water damage to windows, door frames, hardwood floors and glass ceiling tiles. "You have to make a decision: Do you want to replace what was? That may not be the best decision. With the new techniques and things we have now, even if they're not real, they will last forever where some of these older things will fall apart,'' she said. ?EUR??,,?(R)?EUR??,,?(R)?EUR??,,?(R) On the Net: Lower Merion Conservancy: https://www.lmconservancy.org