THE BERLIN WALL will be 20 years old on Thursday. That means all of us who were there are 20 years older and, if not wiser, at least far enough away from those tumultuous days to examine dispassionately how it really was.

It was, first of all, confusing. Certainly, as we stood at Potsdamer Platz on that muggy, overcast Sunday morning we didn't think the damn thing would be around for 20 years. It didn't even start as a wall. Just hundreds of East German construction workers ripping up streets and laying down concertina wire. They actually were closing off a city, or at least their part of it.

We looked on in wonderment with an undercurrent of rage that no one in the West seemed to have the foreknowledge that the Communists would do it. How do you keep a logistical enterprise of that magnitude secret, anyway? Especially when virtually every American civilian in West Berlin (so we thought) had a CIA connection? Didn't we know, or didn't we care, or did we not care enough to make a big case out of it?

All the construction activity we witnessed that day was taking place on their side of the sector boundary, well back from the line, as though anticipating cries from the West that their action would be judged as provocative. The Communists thoughtfully did not close East Berlin entirely. They permitted a few East-West crossovers to remain open, observing to the letter a four-power agreement guaranteeing "access" to the various sectors.

It became a consuming matter of principle for the United States to test that access over the next several months, sending jeeps and official limousines on regular sorties into East Berlin. To my knowledge, the East Germans never made an effort to stop them. There was no reason to, because the rationale for the wall was entirely defensive.

East Germany was hemorrhaging. Most of the refugees who had shown up in a veritable flood were the irreplacable sort whom the East Germans desparately needed at home: engineers, doctors, laborers, farmers. Thousands of them arrived at the Marienfelde refugee camp in West Berlin every morning. The influx provoked a nasty disagreement in the West. There were those like press lord Axel Springer, whose penny tabloid Bild-Zeitung cried for the East Germans to come ober, to enjoy the fruits of freedom. More responsible voices, expecting some sort of Communist crackdown, urged potential refugees to think again, to stay on the farm and the hospitals and the classrooms. There were many ordinary West Germans who agreed with the responsible voices, because refugees got preferred treatment for jobs, housing and social benefits. Too many newly enfranchised West Germans were taking too big a slice from the prosperity pie.

Sealing off East Berlin came as a shock, but there was no attendant fear, at least for a while. We continued to enjoy weekend sailing on the big city lake, the Wannsee, hiked through the Gruenwald forest, window-shopped along the glittering Ku'damm. And there was the added thrill that we were living through an Historical Event. You were reminded of that incessantly. Jack Paar brought the "Tonight" show into town. Ed Sullivan did an entire program from the Sport Palast. Air Force planes at Tempelhof kept disgorging congressmen (who must have pooled their speechwriters) denouncing the wall, celebrating the courage of the Berliners.

Lyndon Johnson came over and passed out hundreds of LBJ ballpoint pens. Attorney General Bob Kennedy arrived with young brother Ted in tow. While Bob was talking to Berlin officials about U.S. determination, etc., Ted was taking a tour of the wall.

He motored into East Berlin where he was photographed showing his passport to the Communist border guard. This action by the president's brother caused hair to curl at the State Department, because the whole Berlin issue was over our policy of nonrecognition of the East German regime.

Hollywood director Billy Wilder was greatly inconvenienced by the seal-off. He had arrived in early August to film the exterior shots of a new Jimmy Cagney movie, "One, Two, Three." The crew was to shoot an important scene Featuring German actor Horst Buchholtz tearing through the Brandenburg Gate on his motorcycle. That was on Saturday, Aug. 12. On Sunday, the trip-hammers and tommyguns appeared and Billy Wilder, who with writer I.A.L. Diamond had planned a light-hearted spoof of Cold War intrigue, found that the prop men had unceremoniously changed the set.

Cagney and the rest of the company hunkered down at the Berlin Hilton waiting for instructions from the Coast. Cagney accepted my invitation to show him the wall, close up, since my press card permitted me to drive beyond the West Berlin control point. "Hey," said the movie tough guy, pointing to a smooth-faced East German guard, "those guys have guns. Let's get back to the hotel."

Alfred Hitchcock was another visitor. He scheduled a news conference at the Hilton's Winter Garden.

"Why are you in Berlin, Mr. Hitchcock?"

"There's a gentleman here who will do the special electronic music for my new movie, 'The Birds.'"

"What do you think about the Berlin Wall, Mr. Hitchcock?"

"I think it's a good place to display signs for my new movie, 'The Birds.'"

Hitchcock's waggish humor was unkindly received in some Berlin quarters, where any reference to the wall had to be uttered in deepest solemnity.

But most of us found that kind of irreverence refreshing. Too many people were turning the wall into a merchandisable commodity. Like the souvenir vendors who showed up over night. And the tunnel purveyors. Building tunnels for profit was indeed a business, cloaked in a mantle of patriotism. NBC did a documentary showing an actual tunnel escape. A classic case of derring-do journalism, but of dubious judgment, since the West Berlin government had appealed to everyone to keep quiet about the tunnels, fearing for the lives of the escapees.

One morning I was approached at the Berlin Reuters bureau by a shifty-eyed man with a Middle East accent. Learning that I was a reporter, he offered to broker a tunnel for my company. He'd supply the plan and the diggers. We'd supply the cash. He seemed surprised by my rejection.

Actually, all of us newspeople profited from the wall. Both in terms of money and career advancement. One is reminded of Kurt Vonnegut's comment that he's the only person who got rich over the firebombing of Dresden. "Slaughterhouse Five" made Vonnegut uncomfortably wealthy. No one in Berlin in 1961 made that kind of killing, but the wall's commercial exploitation seemed limitless, so long as the story stayed on the front pages.

If I were to do a docudrama on the Berlin Crisis, I would have to include Tony Gubanow, Pravda's chief of bureau in East Berlin. We shared lots of good German wine in West Berlin bars during that period. Even then, we knew that any Soviet reporter with access the West did double duty for the KGB.

It was quite exciting to be courted by Tony. He had us over to his place once to meet his wife, a Nina Khrushchev look-alike, and their two tow-headed sons. The boys kept pointing to us, yelling, "Amerikanski, Amerikanski." Tony never brought his wife over to West Berlin. She was always "indisposed."

He would show my wife and me color prints of his vacations on the Black Sea. We'd tell him about the great beached on Long Island. We studiously avoided a discussion of the wall or the relative merits of our two systems. One night, we both got looped and I drove him to the Friedrichstrasse crossing. It was an October evening, and it was at the time of the Tank Confrontation. We had a half-dozen Pattons training cannon muzzles on their T34s, which were positioned directly across the sector line, pointing at us. Tony managed to weave between the Pattons, report to the East German control station and disappear into the fog. Back home, in Karlshorst, he would sober up and presumably file two reports, one to Pravda, the other to his KGB control, neither of which could have provided exciting reading unless Soviet submariners would have found my description of Jones Beach useful.

My TV docudrama also would include a scene on border watching. The newspeople would assemble at Checkpoint Charlie on "stake out" and ruminate over the possibility that one of the tankers -- U.S. or Soviet -- might do something really dumb, like pulling the lanyard and starting World War III. I really doubted that the GIs were equipped with live ammo. "Seriously," I yelled up at a corporal whose head was poking out of one of the Pattons, "you don't have a live round in the breech, do you?"

"Damn right," he said. "All I gotta do is pull the string and . . . WHOOOM." For the first time since the crisis began, I felt my stomach turn. It turned again when I saw that many of the troops liked to booze it up at one of the bars that fringed Friedrichstrasse. All it would take would be one juice-up GI in a frenzy of patriotism to pull the string and . . . WHOOM! I wondered if the vodka-snorting Ivans in their T34s across the way were also having a good time.

Our daily lives changed little during the crisis. There really was no sense of doom hanging over the city, as we were told there was by the TV and newspaper guys who would fly into Tempelhof for a weekend, sniff the political air, get zonked at the Hilton bar and fly back to London or New York to do their lurid pieces.

True enough, there were some irritations. Soviet jets liked to shadow commercial planes using the air corridors. Khrushchev would make occasional noises about transferring Soviet authority to the East Germans, an act which would be viewed as a complete abrogation of the deal made in Potsdam to provide for joint allied rule in Berlin.

There was a big influx of marks from Bonn and dollars from Washington to keep the city viable, and residents were given generous tax credits. Thousands of smart Germans kept a Berlin address but lived in Munich or Frankfurt to reap the advantage of those credits. No one during that time felt threatened. Actually, we felt coddled and cozy.

There were Ella Fitzgerald concerts in the Deutschland Halle. There were Van Cliburn recitals and a sparkling production of "My Fair Lady" and candlelit chamber music at the Charlottenburg Palace. New York's "Living Theater" got State Department funds to so some avant garde works at the Schiller, and it was possible to drive into East Berlin for some surprisingly impertinent cabaret at the Distal.

There was plenty of boozing and sleeping around, a circumstance attributed by some to a "Titanic" syndrome. But Berin always had a reputation for loose and easy living -- as close to insouciance as you'll find in a country renowned for its industry and reserve.

yby 1963 the wall had metamorphosed pretty much to the shape it has today. It lacks a patina and a bronzed inscription, but in every other sense it is a monument. Millions come to see it and take its picture.

Many who weren't even around in 1961 stare blankly. Others look in awe, because it is a huge, ugly thing. Twenty years ago there was brave talk about tearing it down. No one talks that way today. Like the famous Victory Column down the street and the radio tower over by the autobahn, the wall is simply there, massive and mute, a tabula rasa for etching in your thoughts and memories.

John Kennedy came to Berlin in June of 1963. He drew a million citizens to the city hall square. His audience did not understand his speech, but they applauded and cheered wildly when he paused, and they went positively crazy when he yelled out, "Ich bin ein Berliner!"

It was an electrifying moment for Berlin and for the soon-to-be-assassinated young president. Kennedy left the city assured (those who still needed assurance) that it would not be forsaken. And it hasn't been. Rather forgotten, though. Big events elsewhere were taking our attention now. Vietnam. Israel. Watergate. All the while, the industrious East Germans were quietly spiffing up their wall. Now they are said to be preparing a big 20th anniversary celebration, marking that muggy day in August when, to frustrate the aggressive plans of the capitalist-militarist clique, they would erect this glorious shield against the forces of antisocialism.

Those of us who were thee on Potsdamer Strasse in August of 1961 will not lift a glass to join in East Berlin's celebration. But we might retire quietly for a solitary glass of wine and recall some memories that weren't all that unpleasant.