IN a stadium in Prague, 20 years ago today, a hundred thousand people, including my father and me, saw something we were not supposed to see. For decades it had been forbidden. The music, we were told, would poison our minds with filthy images. We would be infected by the West’s capitalist propaganda.

It was a cool August night in 1990; the Communist regime had officially collapsed eight months earlier, when Vaclav Havel, the longtime dissident, was elected president. And now the Rolling Stones had come to Prague.

I was 16 then, and to this day I recall the posters promoting the concert, which lined the streets and the walls of the stadium: “The Rolling Stones roll in, Soviet army rolls out.”

Soviet soldiers had been stationed in Czechoslovakia since 1968, when their tanks brutally crushed the so-called Prague Spring. My father was 21 at that time, dreaming of freedom and listening to bootlegged copies of “Let’s Spend the Night Together.” But it would be more than two decades before he would get to see the band live. During those years, you had to tune into foreign stations to hear the Stones. Communists called the band members “rotten junkies,” and said no decent socialist citizen would listen to them.