A prominent family with historic ties to the Gettysburg National Military Park in south-central Pennsylvania sued the U.S. government Thursday in an effort to reclaim a valuable collection of Civil War artifacts.

According to John Fenstermacher, the lawyer for the family, antiquarians value the 38,000-piece collection at more than $50 million. In a statement, he said the National Park Service has allowed the collection, the largest of its kind, to deteriorate badly.

The lawsuit was filed in federal court in Harrisburg, PA, on behalf of Angela Rosensteel Eckert and six of her relatives. It names as defendants, among others, Interior Secretary Bruce Babbitt and Robert Stanton, director of the National Park Service, which operates the park.

The legal action represents the latest chapter in the long-running battle over Park Service plans to build a $39.3 million visitors center and museum on the historic battlefield. The agency plans to join with a private development group to build the new visitor complex, which also would house commercial enterprises, including a 300 seat cafeteria.

Eckert and many other preservationists strongly oppose the plan. The existing visitor center once served as her home. Her father, George Rosensteel, built the house in 1920. Under the Park Service plan, the center would be demolished and the artifacts moved to the new complex. That complex would be run by a private foundation under Park Service supervision.

The Park Service bought the house in 1971 for use as a visitor center. That same year, members of the Rosensteel clan, including Eckert, donated the artifacts to the government. Her great-uncle, John Rosensteel, began collecting the artifacts immediately after the three-day battle ended in July 1863.

Eckert, 80,who still resides in Gettysburg, said in an interview that the Park Service had failed to take care of the artifacts. "What we want is just to preserve what my parents gave to the United States of America," she said. "We want it taken care of for future generations."

At the time of the gift nearly three decades ago, she said, the Park Service made a verbal commitment to the Rosensteel family that the artifacts would never leave the control of the government.

The Park Service said Thursday that there were no conditions attached to the gift. The agency also said it had spent $553,500 since 1993 to preserve the collection and planned to spend an additional $150,000 this year.

The collection includes rifles, cannons, drums, uniforms, maps, photographs and paintings. The lawsuit demands that the artifacts be returned to the family or be moved to a facility with heat and humidity controls that would prevent further harm.

The Park Service acknowledges that climate conditions in the center are not adequate and has cited the problem as a principal reason why a new complex is needed. Those conditions have left some artifacts rusted or brittle.

In the lawsuit, Eckert and other family members cited a letter sent to her last September by Stanton of the Park Service. He wrote that the "lack of central heat and air conditioning and the lack of humidity and dust controls are putting the artifacts at risk." The suit also referred to a 1971 letter in which an official of the Park Service promised Eckert's mother, Emily Rosensteel, that the collection would "always" be maintained at "high standards."