I AM WALKING THROUGH the hallways of the FBI Building, taking the public tour. I take notes furtively, somewhat afraid the guide in the blue blazer will spot me and ask what I'm doing. The guide tells us to make a left turn at the windown and proceed down the hallway where he'll join us. I am the first in the group to make the turn. I am the first to see it. I am momentarily startled.

It is a desk. On the desk is a lamp with a pen set built into the base. There is a tray of mail and a tan telephone with a small bronze plaque on the back of it. I think I can make out the word "Indianapolis," but that is all I can read. The desk is wooden and to its right is standing on American flag, to the left a Justice Department flag. It is J. Edgar Hoover's desk, and now it is on display with the death mask of Dillinger and the guns in the gun racks, and all the people who work behind the glass so tourists can watch them peer into microscopes just like they do in the movies.

I stand before Hoover's desk until the rest of the tour group catches up. The guide steps to the front of the group and tells who the desk belonged to. He points to a picture of Hoover taken in the 1930s, hat slouched over his face, and another taken in 1972, the year he died. The guide says that Hoover served 42 years as FBI director, and then he asks if there are any questions. There are none. The tour moves on.

No questions! No questions about the famous files or the buggings or the inflitration of leftist groups. No questions about the man who cowed Presidents and left congressmen quaking in their shoes. A man so secure in his job that he had the guts to tell Richard Nixon's aides to buzz off when they came to him with their silly bugging plans.

So I hung back and waited for the next tour group to approach the desk and they, too, had no questions. In fact, you could tell that they considered this stop a diversion. They were on the way to the famous labs and firearms demonstration and they wanted nothing to do with the desk of a dead man.

The truth is that I expected something other than that. I expected questions and I expected that the FBI itself would pay more attention to Hoover than it does with its tour. He is mentioned twice. Once at the very beginning when you are led to a display concerning the gangster era and once at his desk. You are told that he personally arrested Alvin Karpas. He is calle Mr. Hoover," and he is credited with the arrest.

And the truth is also that I thought may be the tour guide would at least mention the name of Clarence Kelley, the present director, more than a couple of times. In the old days, on the old tours, you were constantly hearing the name of Hoover. But Kelley is also more or less missing. He greets you in a film in which he manages to flub his lines and never look you in the eye, and then he is gone.

The reason I went down to the FBI Building in the first place is that I has suspected taht something was up - that the Hoover era was really over. What tipped me off was the arrest recently of a former CIA employee for allegedly trying to sell secret documents to the Russians. The whole caper was something of a joke. The man allegedly took the documents to a building used by the Russians in Washington and left it outside the gate with a note. A Russian guard spotted the box, thought it might contain a bomb, and called the police.

I was in the office when the FBI called and said it would hve something to announce at a 7 p.m. news conference. You might have read past the important information. You do not hold a press conference at seven at night. You do not hold a news conference when Walter Cronkite is putting on his coat, when TV anchormen all when papers like The Washington Post are fast over the East are having their makeup removed, approaching deadline of the first edition and when other newspapers are already closed for the day. If there was one thing J. Edgar Hoover knew, it was deadlines.

So I went down to the building they have named for Hoover and joined the tour. They move off every 15 minutes, and on the day after Thanksgiving, for instance, 6,000 persons moved through the building. They were told about law enforcement techniques and shown the guns and then taken to a shooting range where some technicians pumped a target full of holes with a revolver and a submachine gun. And if they were like any of the tour groups that I saw, they paused before Hoover's desk and asked no questions.

He was only a legend in his own time.