Abraham Lincoln, a 6-foot-4 bearded specter with dreaming eyes and a grave mien, still walks in Washington on this date, 120 years after his assassination.

* He lingers in the East Room of the White House. A week or so before the tragic event, he dreamed that he lay in state in that room, dead from an assassin's bullet.

* His presence is felt in Ford's Theatre, where John Wilkes Booth shot him with a .44-caliber single-shot percussion Deringer pistol and then leaped to the stage in the most dramatic of theatrical entrances.

* His hard-fought death on April 15 still produces chills in the House Where Lincoln Died, across the street from the theater. He was taken there lest moralists disapprove of a president dying in a godless theater on Good Friday.

Another spirit follows the escape route of his assassin:

* The Mary Surratt house on H Street NW, "the nest where the egg of treason was hatched."

* Dr. Samuel Mudd's house just north of Bryantown, Md., where the good doctor treated Booth's broken leg.

* The site of Garrett's Barn near Port Royal, Va., where Booth was shot as he stood in a burning barn. His executor, Sgt. Boston Corbett, earlier had castrated himself in penance for speaking to a prostitute.

A letter usually safeguarded in a neat manila folder in the Georgetown University Library raises new questions about the Lincoln assassination conspiracy.

The letter has never before been published and is apparently almost unknown to history, said Nicholas Scheetz, curator of manuscripts. The letter is currently on exhibit as a part of "This One Mad Act."

Edwin M. Stanton, Abraham Lincoln's secretary of war, wrote it on Dec. 19, 1865, to the leaders of Congress. He was the man who virtually took over the U.S. govern-ment in the emergency following the president's assassination. At the time, there were rumors, disbelieved today by Lincoln experts James O. Hall and John K. Lattimer, that Stanton had hired Booth and his cohorts to assassinate Lincoln. Stanton wrote on War Department letterhead:

"After deliberate reflection, I find that for reasons dwelling in my own heart and needless to be exposed, [italics added] it will be impossible for me to perform the high and solemn duty of delivering an address on the occasion of the funeral honors designed to be paid by Congress to the memory of the late President Abraham Lincoln . . ."

Was his heart full of guilt? Emotion? No one will ever know.

Lincoln's assassination, the first violent death of a president, is a local story and a national myth. Nearly a century and a quarter after his death, people seek mementos as if they were fragments of the true cross.

Lincoln autographs and material bring far higher prices than that of George Washington or John F. Kennedy, says Mary Jo Kline, Sotheby's American manuscript expert.

Frank Williams, a great Lincoln collector, points out that last month, at Sotheby's in New York, Malcolm Forbes paid $104,500 for a signed photograph of Lincoln and his son. And a printed copy of the Emancipation Proclamation, signed by Lincoln and his secretary of state William H. Seward, was sold to Forbes in October at Sotheby's for $297,000.

A television program, scheduled for April 25 on ABC's "20/20," follows the route of the best known of the men who claimed to be John Wilkes Booth after his official death. ABC's candidate was a man called John St. Helen who quoted Shakespeare in Gran Bury and Glen Rose, Tex., bars, and who confessed -- on what he thought was his deathbed -- that he was Booth.

He had changed his name to David George and committed suicide in Enid, Okla. His body was mummified and exhibited in sideshows. (The Georgetown Library exhibit includes photographs and letters on the subject from the E.H. Swaim Collection.) Hall, interviewed with Scheetz and historian Terry Alford, doesn't believe in the Booth pretenders, either.

Reason, evidence and experts say Stanton was not a part of the conspiracy, and that the poor soul who killed himself, after claiming to be Booth, was only a pretender. But the deaths of great men can never be thought simple, says Scheetz. Such events cry out for conspiracies of assassins.

Dreams, myths, ghosts, rumors -- no town in the United States is as haunted as Washington, where, in a second, the fate of a nation was changed in the flight of a bullet.

But the objects in three exhibits at great Washington Lincoln collections, the Library of Congress, Ford's Theatre and Georgetown University, convey a realness that brings tears to the eyes or chills to the spine.

Peer in the glass exhibit cases as if you were looking in a crystal ball, revealing the Washington of old: At Georgetown University

At least one object for every year since the event is on exhibit at the library through July 7. Many are from the collection of John K. Lattimer, the author of "Kennedy and Lincoln," who is scheduled to speak today to an invited group at the opening.

Of the eight individuals tried for complicity in "the crime of the century," three had been Georgetown students, points out Terry Alford, who organized the current exhibit and wrote its catalogue. Alford is author of "Prince Among Slaves."

Other objects:

* The Georgetown "entrance book of 1850-1895" has notes by the Jesuits about former students' later careers. Beside the name of David E. Herold (executed with three other convicted conspirators), is the simple note, "Alas!"

* The bloodstained half of Lincoln's collar was cut from his neck by the first physician to reach him, Dr. Charles A. Leale. William T. Kent had been playing pool nearby. He ran to the theater and to the president's box and lent his knife to cut open the collar. Later, he missed his keys and he and Newton Ferree went back to the box. Kent found Booth's Deringer pistol, Ferree took the collar.

* The metal key marked DC/7 to the broken lock of Dress Circle 7, the presidential box.

* A letter from Booth to a friend, written in 1854, tells of his fight with a tenant at his family's Tudor Hall in Harford County, Md. ". . . he called my sister a Liar. I knocked him down which made him bleed like a butcher . . . he then warrented me and in a coupple [sic] of weeks I have to stand trial for assault and battery."

* A rope with five knots (the men were hung with seven knots) with a copper band engraved with the name Mary E. Surratt. After the execution, the hangman, Capt. Christian Rath, wrote that "the rope had cut deeply [into her neck]. That rather sickened me."

* At the Library of Congress

Bits and pieces from Lincoln's pockets on the night of his assassination -- given by his granddaughter, Mary Isham, daughter of Robert Todd Lincoln, are shown for only the second time.

This exhibit, organized by James Gilreath, the Americana specialist in the library's Rare Book and Special Collections section, is on view through the spring. This is only the second time the objects have been shown.

* A pair of gold-rimmed spectacles, one bow mended with string, bring vividly to mind the picture of the president interrupting his deliberations -- at a critical time in its history -- to fix his glasses, with only a bit of string handy. But Lincoln must have had his doubts about his repair work. He had other spectacles with him -- a tiny, folding pair with their own silver case, now tarnished to a pewter darkness.

* The white Irish linen handkerchief -- "A. Lincoln" sewn in an amazingly small and neat cross-stitch -- is neatly folded. Either the handkerchief was laundered and ironed or else he had no need, that unhappy evening, to use it.

* The brown leather wallet, lined in purple silk, with its own pencil and pockets for notes, currency and railroad tickets, must have been his best evening equipage. Like many presidents and rich men, Lincoln seems not to have carried spending money -- unless it's long since spent. Ulysses Grant, Gilreath suggested, may have given Lincoln the bill when the president visited Petersburg and Richmond earlier that month.

* No watch, but a watch fob, a small lantern-shaped piece of gold-bearing quartz.

* Eight newspaper clippings, still in fine readable condition (newsprint then had less acid in it and lasted longer). You can imagine him keeping them, a curious collection from various papers, to show to friends he might meet in the evening.

The clippings report: an emancipation ordinance passed in Missouri; a letter by British reformer John Bright, favoring Lincoln's re-election; an address by the Rev. Henry Ward Beecher that caused a newspaper to declare of Lincoln, "There is a general feeling that, after a term of war he is entitled to a term of peace"; General William Tecumseh Sherman's orders for his "War Is Hell" march through Georgia; a defense of Gov. Gamble of Missouri, charged with "copperheadism"; a letter, said to have been found on the street in Brandon, Miss., saying, "We are a defeated and a ruined people, shorn of our strength, powerless"; a probably apocryphal "Conscript's Epistle to Jeff Davis"; and a series of resolutions passed at a political convention.

* The final evidence that little problems beset great and small alike is the single shirt button or cuff link or collar button, inscribed with the inital "L." Under what circumstances did it fall off? Was it one of a pair? No one is around who knows. At Ford's Theatre

* An exhibit organized by Jennifer B. Lee, curator of the McLellon Lincoln Collection at Brown University. Open through April 30.

* Five Thomas Nast drawings about the Civil War era.

* A poem that Lincoln wrote after the Battle of Gettysburg. His second inaugural address.

* A campaign badge.

* And many photographs of the period.