Stacks of recently cut tree trunks wait to be hauled away from the area around Devil's Den. A modern building on Cemetery Ridge that sits close to the scene of Pickett's Charge stands empty, facing demolition. On another part of the battlefield, construction workers are building a large structure shaped like a round barn.

With an estimated $131 million in projects under way, the fields and farms around this small town in southern Pennsylvania probably haven't seen this much sustained activity since the three crucial days in July 1863 when 165,000 Union and Confederate troops clashed here in what is widely considered the turning point of the Civil War.

Gettysburg is at the forefront of an effort to restore many Civil War battlefields to something more closely resembling their appearance when they were the scenes of bloody struggles between the forces of North and South.

"If you can think of an historic landscape the same way that we're used to thinking of historic structures, the whole reason for doing this follows suit," said John Latschar , superintendent of the 6,000-acre Gettysburg National Military Park. "It's as important at Gettysburg as not adding stucco to Independence Hall." At the heart of these rehabilitation projects is a task that would seem an odd undertaking for the National Park Service, which administers many of the battlefields: cutting down hundreds of acres of trees.

In the 142 years since the war's end, fields that were once farmed have fallen fallow, allowing trees to grow and obscure what were clear lines of fire in 1863. At Gettysburg, where Civil War cannon are placed in the locations that artillery occupied during the battle, that has given rise to some odd juxtapositions.

"We had batteries of artillery pointing straight into mature stands of trees," said Gettysburg spokeswoman Katie Lawhon. "And over the years, we had lost a lot of fences. At Gettysburg, a fence could be the difference between life and death." Under a 1999 restoration plan, the park service will cut down 576 acres of woodland at Gettysburg that did not exist at the time of the battle, and replant 115 acres of trees that were there but have since disappeared. This year, work is focusing on clearing out trees around Devil's Den, a rocky outcropping that saw bitter fighting, and along a section of the Confederate line on Seminary Ridge.

In the course of the project, foresters are working to preserve "witness" trees, which were present on the gently rolling Pennsylvania hills when the forces of Confederate Gen. Robert E. Lee and Union commander Gen. George Meade collided.

The ambitious plan also calls for rehabilitating or reconstructing nearly 10 miles of historic farm lanes and roads and restoring 39 miles of fences, hedgerows and other field boundaries. And one of the most pervasive anachronisms on the battlefield--overhead power lines--are being buried.

Similar but smaller efforts have been undertaken at many other Civil War battlefields, including Antietam in Maryland, Chancellorsville and the Wilderness in Virginia, Chickamauga in Georgia and Vicksburg in Mississippi.

"It's much more difficult to explain the events that occurred on these battlefields if they don't look like they did during the Civil War," said Jim Campi of the Civil War Preservation Trust, a non-profit group that works to preserve Civil War battlefields. "If people can't see what decision-makers could see, they can't grasp what happened." But the park service and the non-profit Gettysburg Foundation, which is raising $125 million toward the project's overall cost, are doing more than restoring the landscape at Gettysburg.

A new $103 million museum and visitors center, designed to resemble a Pennsylvania farm to help it blend into the historic landscape, is under construction to replace the park service's cramped and outdated facility, which sits across the road from the national cemetery where Abraham Lincoln delivered the Gettysburg Address later in 1863.

The new building, which will open in April, will contain more extensive and updated exhibits, telling the story of the battle from the standpoint of the commanders, the common soldiers, the citizens of Gettysburg and the war correspondents who covered the battle.

Among the highlights of the new museum will be the newly restored Gettysburg cyclorama, a 360-degree painting that depicts the key moment of the battle, Pickett's Charge, when Rebel soldiers came close to breaking through the center of the Union army's position on July 3, the last day of the battle.

The massive 1884 painting, by Paul Philippoteaux, measures nearly 360 feet long and 27 feet high, and it weighs more than three tons. A team of conservators is repairing extensive damage and adding a missing 14-foot strip to the top of the cyclorama. Foundation spokeswoman Dru Anne Neil said the $11.2 million project, which will be finished in September of 2008, is the largest art conservation project in America.

On such a historic site, controversy is almost bound to accompany any change. A group of architectural preservationists has sued the park service over its plans to demolish the building that used to house the cyclorama, a striking 1962 concrete structure designed by famed Modernist architect Richard Neutra. The building is on the National Register of Historic Places.

"It's too important a structure to demolish and just throw away," said Christine Madrid French, president of the Recent Past Preservation Network, the Arlington, Va., group that filed suit, charging that the park service did not study alternatives such as moving the building. "The building has a lot of life left in it, and a lot to give to people in terms of helping them understand the architecture of the time." But park service officials say the Neutra building never functioned well, citing a leaky roof and inadequate temperature and humidity controls that contributed to the cyclorama's deterioration.

Latschar, the Gettysburg superintendent, said about 970 Union soldiers were killed, captured, or wounded in the area around Neutra's cyclorama building and the current visitors center, adding to the importance of returning that part of the battlefield to its 1863 condition.

No major action took place at the site of the new museum and visitors center.