It has been called the "saddest acre in America." The graves here in Section 60 at Arlington National Cemetery are fresh, many decorated with autumnal mums and pumpkins.

Family and friends wander among the clean white headstones, often sitting down in the new grass to spend time with loved ones killed in the wars in Iraq and Afghanistan.

Robert Poole has seen the tableau played out dozens of times. As author of the new book On Hallowed Ground: The Story of Arlington National Cemetery (Walker, 352 pp., $28), published in time for Veterans Day, Poole spent the past few years wandering Arlington's 624 acres, from Section 60's new graves in the cemetery's flat and remote south end, to the first military grave (year: 1864), perched on a hillside to the far north.

"It's easy to get lost here," says Poole, 60, a former executive editor at National Geographic. "There are all kinds of nooks and crannies. But I just wandered. I did a lot of that. You get your best stuff that way."

Arlington remains America's premier military cemetery, a reassuring and iconic piece of land that gives comfort to the families left behind, people like Thya Merz of Brooklyn, whose son Julian Brennan was killed by a roadside bomb in Afghanistan Jan. 24. He was 25.

She "knew right away" where he'd be buried.

"His grandfather is buried here," Merz said while visiting her son's grave recently, a large round button bearing the young Marine's face pinned to her coat. "He always said his grandfather inspired him to be a better man." (His grandfather, James Brennan, a Marine who fought in World War II, is buried in Section 66, just across the road from Section 60.)