The rain is falling straight down on the endless rows of white headstones at Arlington National Cemetery. The ground is covered with leaves, and the bare trees gleam black. Big yellow sycamore leaves plummet one by one to litter the carefully swept walkways. Off back from the road, among the ranked stones, men in slickers are setting up an awning for a burial ceremony.

About 15 burials a day are held here, weekdays. During the Vietnam war as many as 37 a day were buried at Arlington.

At the Tomb of the Unknowns people are working with quiet purpose, getting ready for the Veterans Day memorial program beginning at 11 a.m., the hour the Armistice began in 1918, and the laying of the wreath by Defense Secretary Caspar Weinberger -- to be one of his last official acts. Already the press scaffolding has been erected next to the tomb, and folding chairs are in place at the amphitheater.

The sentry on duty strides through the rain: 21 steps in the eerie gliding ceremonial pace; turn; pause 21 seconds; turn; march back. By regulation, he is over six feet tall, has a 28-inch waist, patrols the tomb for an hour before being relieved. In the summer, sentinel duty is 30 minutes; at night it is two hours.

The sentry wears wool, even in August, because it holds a crease, and before he goes on his buddies tuck away all wrinkles in the jacket so it looks tailor-made, every button and bit of brass newly shined, every speck of lint plucked off.

On bright days the sentry wears dark glasses against the glare of white marble. Not today. The soldier on duty, with rain dripping from his visor and streaming down his M14 rifle and soaking his pant legs, is Pfc. John Ahearn of Pensacola, Fla.

The large white tomb he is guarding -- and he does guard it, and sometimes will confront an unruly visitor, for this is a working guard post -- overlooks the long slope that leads to the capital, invisible now in the fog. On good days there are crowds here, but today the sentry walks alone. There is no sound but the heel clicks, the slap of white-gloved hand against rifle, the steady splash of rain on stone.

The Unknown Soldier was picked from 1,237 unidentified American dead in World War I. Four anonymous bodies were exhumed from different cemeteries in France, and a decorated infantryman, Sgt. Edward F. Younger, was chosen to pick one of these.

"I went into the room and walked past the caskets," he said, as reported in Philip Bigler's book about Arlington, "In Honored Glory," just published by Vandamere Press of Arlington. "I walked around them three times. Suddenly I stopped. It was as though something had pulled me. A voice seemed to say: 'This is a pal of yours.' "

He placed a white rose on the coffin.

The Unknown Soldier was buried Nov. 11, 1921. President Warren Harding presented him the Congressional Medal of Honor and the Distinguished Service Cross. Chief Plenty Coups, a Crow Indian attending the ceremony to represent all native Americans, stepped forward unannounced and put his war bonnet on the sarcophagus.

Since then three other unknowns have been buried close by: from World War II, Korea and Vietnam.

On this rainy day there are few visitors at Arlington Cemetery, no lines of people at the Kennedy graves, no chattering groups. It is quiet. Rain drips from skeletal branches, and leaves mat the ground between the headstones. The even rows follow the curves of the hills to the horizon.

Off in a glade, beneath a huge oak, three people stand by a grave: a young couple and an older woman with an umbrella. They do not move. They do not seem to be talking.

Well over 3 million people a year visit Arlington. Two hundred thousand Americans are buried on its 612 acres, and -- with tier burials, tightened eligibility rules and land acquisitions -- the cemetery can continue to receive American military dead until about 2020.

The first burial was on May 13, 1864, when Pvt. William Christman, 21-year-old Pennsylvania infantryman, was put to earth near the old Lee plantation. He had died of peritonitis barely two months after enlisting.

Not everyone was pleased with this burial, for the plantation had been confiscated on dubious grounds and auctioned to the federal government for $26,800. Twenty years later the Lee heirs regained title through suit and sold the estate back to the government for $150,000.

Eventually, the dead from earlier wars were moved here, so a visitor can find smooth-worn Revolutionary War markers, "wolfstones" laid flat to keep wolves, it was said, from digging into them. On many, the name is completely weathered away.

Others buried here never were known. There are 4,725 anonymous dead at Arlington, most from the Civil War, when a body had one chance in three of not being identified, writes Bigler, an American history scholar and teacher who for two years was the official cemetery historian. The bones of 2,111 soldiers uncovered at Bull Run were brought here and marked with a sarcophagus in 1866.

On a prominent knoll are rows of stones with cryptic notations: "C. Williams, civilian." "Augusta Hawkins, citizen." "Unknown." These are the dead from Arlington Village, a community of freed slaves, which was crowded off the map by the encroaching columns of headstones near the turn of the century. More than 3,800 former slaves are buried at Arlington.

Among those graves are others marked U.S.C.T., for the "colored troops" who served the Union. A few fell in the Indian wars.

Most visitors want to hear about the famous. Two presidents are buried on these slopes: Kennedy and Taft. The Kennedy funeral on Nov. 25, 1963, was one of 23 that day, and the page in the schedule book is full of erasures and notations, for the burial plans were changed several times, and other ceremonies had to be pushed back or forward.

There are empty spaces before and after the 3 p.m. slot. The name there, written in light pencil: John F. Kennedy F-H/C, meaning full honors with caisson.

Names. A lot of generals and admirals. Sheridan. Pershing. Peary. Bradley. Halsey. Marshall. Rickover. Maxwell Taylor, who parachuted into Normandy on D-Day. (One of his men in the 82nd Airborne was Raymond J. Costanzo, now superintendent of the cemetery.) Medal of Honor winners, 325 of them at last count. The Iran hostage rescue mission's dead. The Lebanon bomb victims. Grissom and Chaffee of Apollo I, Scobee and Smith of Challenger.

And Joe Louis, and actor Lee Marvin, who had won the Purple Heart, and newscaster Frank Reynolds, with a Silver Star. Michael Strank, Ira Hayes, Rene Gagnon, who helped raise the flag at Iwo Jima.

Confederates buried at Arlington just after the Civil War were marked "Rebel" in the old ledgers, for feelings still ran high. During World War II three prisoners, two Italians and a German, died of illness and ended up here. Every year on All Souls' Day the Italian Embassy puts flowers on the graves of Arcangelo Prudenza and Mario Batista, a long way from home.

There is the curious story of Ignace Paderewski, the great Polish pianist and national leader, who died in New York in 1941. President Roosevelt offered sanctuary for the body "until Poland is free." It still waits, like King Arthur, in a vault beneath the mast of the USS Maine. In 1963 President Kennedy dedicated a plaque memorializing the venerable statesman.

Arlington is a big place. In some older sections there are privately purchased monuments: columns, busts, marble figures, even a cannon. There are sections of close-standing memorials to the missing, and tiny graves for children, who for years were buried separately from their parents to save space.

But mostly there are those even rows of white stone with name and rank and religious symbol. (For atheists, there is a whirling atom.) Privates and generals, the young who died in combat and old soldiers, medal winners and rear-echelon clerks ... they mingle here as they never did in life, lined up in modest uniformity, in silent community under the stones, under the grass, under the leaves of November.