A groundbreaking ceremony will be held next week for a memorial to the victims of the Sept. 11, 2001, attack on the Pentagon, marking a milestone in the project's nearly five-year fundraising effort.

Defense Secretary Donald H. Rumsfeld is among 150 guests, including family members, expected to attend the June 15 invitation-only ceremony, which will be held at the memorial site on the Pentagon's west lawn, the president of the Pentagon Memorial Fund said.

"It is one step toward completion of the memorial," said James J. Laychak, who lost a brother in the attack. "It gets us closer to the vision that I have of all of us family members sitting in a quiet corner at the completed memorial watching everyone enjoying what we helped create."

About $10.8 million has been raised for the memorial's construction, which is expected to be completed in September 2008, Laychak said Monday. The goal is to raise $22 million for construction and another $10 million to maintain the memorial.

The majority of the money has come from private donations, Laychak said. He said the memorial fund recently got a grant of nearly $1 million from the federal government.

The memorial will have 184 low slung metal benches, one in memory of each victim of the Pentagon attack. The benches will be perched above small reflecting pools of water, and the display will be arranged to provide a timeline of the victims' ages.

About 80 paperbark maple trees will shade the memorial, which will sit on about 2 acres 165 feet from where American Airlines Flight 77 hit the building.

Architects Julie Beckman and Keith Kaseman, who won a worldwide competition to design the memorial, also will attend the groundbreaking.

"It is a huge milestone, and I am very excited about it," Beckman said. "It is something that we have been waiting for, and it is timed to go along with real construction that is beginning on the site. We are just thrilled."