MOSCOW -- One day in 1928 they arrested Oleg V. Volkov and brought him in a horse-drawn cart to the Lubyanka, headquarters of the Soviet secret police. It was the beginning of a 27-year odyssey through the Gulag.
Yesterday the white-bearded writer returned to the square in front of what is still the KGB building -- to help unveil a simple stone memorial inscribed: "To the memory of the millions of victims of the totalitarian regime."
"I never thought I'd live to see a time when I could not only tell the truth about what happened, but see a monument to those who will never return," the 90-year-old Mr. Volkov declared.
But he reminded an audience of several thousand Gulag survivors and relatives, many holding candles and some weeping, that the process of repentance remains incomplete.
He pointed to the towering statue of Felix Dzerzhinsky, first chief of the secret police. The statue, in the middle of what is still called Dzerzhinsky Square, must come down, he said.
"Don't forget the lessons of the past," he said. "Don't forget the victims of the terror."
The gray stone was brought to Moscow from the camp in the Solovetsky Islands in the White Sea, which opened in 1920 in what had been a monastery. Solovetsky is seen by many historians as the birthplace of the system of state terror that later, under Josef V. Stalin, swallowed tens of millions of innocent lives. Mr. Volkov is one of the few living veterans of Solovetsky.
The modest memorial is the first monument in Moscow to the victims of what several speakers called "Communist terror." It is a hard-won victory against the powerful forces in Soviet society who resist the full exhumation of the crimes of Stalinism and the examination of their relation to the 1917 Bolshevik Revolution.
The ex-prisoners, their relatives and activists of the Memorial society, which organized the event, gathered at midafternoon at the north end of Lubyanka Street. Many held up signs identifying their camps or wore their prisoner numbers on their coats, hoping to find fellow survivors.
The crowd then walked slowly the half-mile to Dzerzhinsky Square. The only sounds were footsteps and a woman's recorded voice, reading from a seemingly endless list of the dead: "Ivan Dmitrievich Leskov, carpenter, shot. Alexander Pavlovich Smirnov, collective farm worker, shot. Lyudmila Alexandrovna Berogaya, engineer, shot . . ."
The survivors' tales were horrific. Irina I. Kalina, 62, an artist, told how her diplomat father was arrested in 1938, denounced by his driver and executed. Her mother was arrested the same year.
At the age of 9, Irina went to live with an aunt and uncle in Leningrad. But the uncle, who worked at a defense plant, was told he was unwise to have a "child of an enemy of the people" living with him. So she was shipped off to another aunt in the far north.
Finally she came to Moscow and entered an art institute. But in 1949 she was dismissed from the institute and arrested: As the daughter of arrestees, she herself was suspect.
She, too, was brought to the Lubyanka, then transferred to Lefortovo prison, where she awaited trial in a frigid stone cell, stripped to her underwear and fed every third day. She then spent five years in the camps, enduring sexual molestation, near starvation and crushing labor before Stalin's death eventually led to her release.
"You must hear this, people," Ms. Kalina declared to a small crowd that gathered around her. "I tell you, you are fortunate that you escaped this. If Stalin hadn't died, all these people you see here today would be dead."
President Mikhail S. Gorbachev has gradually permitted the truth to be told about Stalinism. But he, and his KGB chief, Vladimir A. Kryuchkov, generally have attempted to limit their condemnation to the Stalin period, preserving the revolutionary leader Vladimir I. Lenin as an idol and dismissing the anti-dissident campaigns of the post-Stalin period as regrettable but lawful.
Many of yesterday's camp survivors stressed the continuity of political repression from the revolution to the 1980s.
Pavel A. Ilyin, 76, was arrested in 1962, at the height of the "thaw" under Nikita S. Khrushchev, who himself had denounced Stalin's crimes.
Mr. Ilyin had written an anonymous letter to a Communist Party Congress criticizing Khrushchev's agricultural policies. It took the KGB three months to trace the letter to Mr. Ilyin's typewriter; he got four years for "anti-Soviet propaganda," he said.
After a religious ceremony consecrating the memorial, many of the elderly camp survivors laid bouquets of flowers at the stone and left for home. But several hundred younger people, many of them members of the militantly anti-Communist Democratic Union, remained on the square, chanting anti-KGB slogans.
Several bus loads of riot troops, kept discreetly out of sight during the main ceremony, appeared in response to the Democratic Union rally. Troops forced their way into the crowd and arrested several people, though it was unclear why they were picked out.
As the troops wrestled demonstrators aboard a bus, the crowd screamed, "Fascists! Fascists!" But there were no large-scale clashes.