Three hundred and twenty thousand men and women lie buried here - the famous and the unknown. They all have one thing in common: they served their country honorably.
"It is a wonderful, terrible place," said author Elizabeth Pryor. "It is wonderful because the history here is monumental. And it's a beautiful place."
Pryor views Arlington National Cemetery through a unique lens - the letters of the man who lived in the house on its grounds, Robert E. Lee.
"He once wrote that Arlington was the place that his feelings were more attached than any other place," Pryor said.
It was in Arlington House, a house built by slaves, that Lee decided to resign his commission in the United States Army and fight for the South.
"The decision he made in this house, in his bedroom on the second floor, forever altered the course of American history," said park ranger Kendall Thompson.
… And the history of this great estate. In time of war its commanding view of the nation's capital, said Thompson, made it more than just a scenic overlook.
"At the time, artillery was pretty accurate to about four miles," Thompson said. "It's around 3.8 miles as a cannonball flies from here to the Capitol."
"This is the high ground that you've got to occupy in a war?" Martin asked.
"Uh-huh, and after Lee left, it was only a matter of weeks before the Army crossed the river and did settle into the house."
More than half a million soldiers died in the most awful war in the nation's history, and it turned Lee's estate into a graveyard.
Private William Chrisman was the first to be buried here. He'd only been in the Army for 90 days. "Died of peritonitis," said Tom Sherlock, the cemetery's historian. "Never saw combat."
Sherlock said no one realized this would one day be a national shrine.
"It was the result of the burial space in and around the city of Washington being exhausted by the sick and the wounded being brought to the Army hospitals here," he said.
Was it an honor to be buried here then?
"It was not," Sherlock said. "You know, today Arlington is thought of in such high esteem. But back during the Civil War you probably wouldn't have wanted a friend or relative buried here because we're basically burying two types of soldiers: unknowns, which one out of every three combat deaths were during the Civil War, and also soldiers whose families didn't have the money to return them home. So it was basically a potter's field."
Just over the hill, more rows of Civil War dead. But these headstones tell a very different story. Many bear the initials "USCT."
"USCT stands for United States Colored Troops," said Sherlock. "And these were some of the first African Americans that were actually allowed in combat roles, during the Civil War. And although that's not a term we'd use today, in the 1860s a black man would have been proud to be called a United States Colored Troops."
"Now, if anybody had a stake in the outcome of that war …" said Martin.
"Absolutely. I can't think of an American soldier that knew the values of fighting for freedom more, because they were literally fighting for their freedom from slavery."
As the slaughter mounted, General Montgomery Meigs, the quartermaster of the Union Army, took his revenge by ordering the dead to be buried in Mrs. Lee's beloved rose garden.
"She said they planted them up to the very door without even common decency," Pryor recounted. "General Meigs personally came here and paced off these graves because he wanted them in full view of the Lees' house."
"Sounds like an act of spite," Martin said.
"It does," she agreed. "It's clear from his own writings that he did have a strong sense of maliciousness, vindictiveness. It's not a nice way to begin a hallowed place."
No one thought of Arlington as a hallowed place until 25,000 people attended the funeral for the crew of the Battleship Maine which blew up and sank in the harbor at Havana, Cuba in 1898. It was that generation's 9/11, and it became the battle cry ("Remember the Maine!") for the Spanish-American War.
What made Arlington the place of honor was another 9/11-like shock - the assassination of President John F. Kennedy and the nationally televised funeral procession as he crossed the Potomac for the last time and was laid to rest at the foot of Lee's mansion.
There is every reason to believe JFK would have approved of the site selected for his grave. He visited here just six months before he was killed.
"The president was taking in the view of the city of Washington, and he said, 'This is beautiful. I could stay here forever,'" Sherlock said.
The burial of President Kennedy was the one event that changed how Arlington is operated as a cemetery.
Requests for burial in Arlington quadrupled, forcing the cemetery to tighten up its eligibility requirements. The number of tourists shot up even more, from one million a year to 9 million in the first six months after Kennedy's burial. It's back to a steady state of between 4 and 5 million a year now, but the eternal flame, along with the Tomb of the Unknowns, is still the most visited site.
The cemetery is busier than it's ever been: 27 to 30 funerals a day, 7,000 a year. The majority of funerals are those of World War II veterans and their spouses being buried each day here.
No one is more deeply steeped in Arlington's rhythms of death and honor than Jack Metzler. He grew up here when his father was superintendent, and now he's the superintendent.
Orchestrating the rigid protocol of 30 funerals a day is a military operation all its own.
"Everything is worked off of a schedule and we reuse the caissons, we reuse the troops, funeral after funeral throughout the day," Metzler said.
"You must worry about one funeral crossing another," Martin said.
"Caissons don't back up. They go forward," Metzler said. "So we have to be very careful that we don't cross caissons or cross processions through the day.
"A funeral here at Arlington Cemetery is a one-time event, so we work very hard to ensure that everything is done correctly the first time."
There are basically two kinds of funerals at Arlington - veterans who have lived out their years, and soldiers who have fallen on the field of battle.
"Burying someone whose time has come, World War II veteran, there's usually a large family, grandchildren, great-grandchildren," Metzler said. "It's a celebration of life. The military sends this individual off in grand style. It's a celebration.
"Now when you go to an active duty funeral, talking about someone who is 19, 20, 21 years old, it's a completely different funeral. Raw emotions."
Which brings us to what is simply known as Section 60, where nearly 500 dead from Iraq and Afghanistan are buried. Here wives leave fresh kisses on their husbands' tombstones, stuffed animals keep the fallen company, and colored stones are a way of showing love.
Ami Miller leaves stones for her brother, Chris Neiberger, whom she visits every week.
"I leave one for my mother and for my father. One for myself. One for my husband. My brother Eric. His wife Ellie. My brother Robert. And my Aunt Susan. It's really the immediate people affected, hurting for him."
Chris Neiberger had just turned 22 the Friday before he was killed.
Three headstones away, at the grave of his fiancé Maria Ortiz, Juan Casiano takes up his weekend vigil.
"I still love her and I miss her so much," he said. He was wearing the hat that she wore when he dropped her off at Fort Bliss, Texas, to go to Iraq.
Ortiz was the first nurse killed in combat since Vietnam.
Why did Casiano choose to have her buried here?
"This is holy ground," he said. "What an honor to be buried here, you know? And I thought, let's bring her here where she can always be remembered. And always having someone paying respects to her for her duty."
Chris Neiberger's father wanted his son buried here. "I think he felt very strongly that Chris would want to be with his fellow soldiers," Ami Miller said. "This is a very honorable place."
The tour buses don't stop at Section 60 - there are no crowds to eavesdrop on conversations between the living and the dead. But people are beginning to find their way to this part of the cemetery.
"Do you mind the tourists?" Martin asked Miller.
"I mind being treated like an attraction, I mind that," she said. "If people want to come and pay their respects and are respectful to me that's OK."
A place of profound sorrow open for everyone to visit. But only those who have served their country with honor are allowed to stay.