The controversial cyclorama building at Gettysburg National Military Park has been granted a reprieve by federal authorities.

The National Park Service agreed to delay demolition of the 1961 building until a federal judge rules on a lawsuit filed two years ago by preservationists who want to save it.

In a letter to a federal judge, a Justice Department attorney representing the Park Service said this week that the agency would continue to seek bids for demolition but would inform bidders that no work would take place until the U.S. District Court judge hearing the case issued a ruling.

The Park Service says the modern building, which sits in the middle of the Civil War battlefield, is an intrusion and an obstacle to the restoration of a section of the battlefield known as Ziegler's Grove.

The circular building, designed by renowned American architect Richard Neutra, was located there to house the massive cyclorama painting depicting Pickett's Charge. The building and the original visitors center also provided tourists with easy access to the site where Union forces defended Cemetery Ridge against Confederate forces on the third day of the battle.

The restored cyclorama painting is now housed in the new Visitors Center, a mile from the battlefield.

Preservationists call the Neutra building a significant work of modern architecture, a rare surviving example of Neutra's civil architecture on the East Coast.

"I'm beyond excited," said Christine Madrid French, a Neutra scholar and president of the Recent Past Preservation Network, the group that filed suit to save it. "It gives preservationists an opportunity to slow the decision-making process."

In 1999, the Advisory Council on Historic Preservation sided with the Park Service's plan, saying the vast majority of the millions of people who had visited the park since the cyclorama building opened came to see the battlefield and not Neutra's architecture.

"There are other Neutra buildings; there is only one Gettysburg Battlefield," the federal panel wrote.

But French and other modern architecture preservationists say all options, including moving the building to a nearby location, should be considered before demolition.

Contact staff writer Amy Worden at 717-783-2584 or aworden@phillynews.com.