LENINGRAD, U.S.S.R. (AP) _ The Communist red flag was taken down from the domed city council on Saturday and replaced with the blue, red and white Russian Federation flag.

All party institutions, including the Smolny Institute - Lenin's headquarters during the 1917 revolution - have been shut since the aborted coup against Mikhail Gorbachev ended Wednesday. Also closed was Lenin's museum.

It seems ironic how quickly communism has become highly unpopular in Leningrad, the former cradle of the Bolshevik revolution.

The party archives and documents have been sealed to assure that papers relating to the three-day coup attempt by hard-liners were not removed.

''They should not only seal buildings belonging to the Communist Party. They should put all Communist officials inside and let them starve there,'' said Yuri Belaev, a university student.

''We have starved enough under communism,'' he added.

A crowd of about 100 people chanted ''Criminals, traitors'' as a black Volga car drove from the Smolny Institute. Black Volgas are cars traditionally used by Soviet officials.

Earlier, in the nearby Lenin Museum, Ivan Visilovsky, a veteran Communist, was wondering why communism was crumbling even in the Soviet Union where it all started.

''I still believe in socialism, but many mistakes have been made since the great Lenin,'' said the 79-year-old Visilovsky, a doorman in the Lenin Museum.

Residents of Leningrad, the Soviet Union's second-largest city, earlier this year voted to bring back the city's pre-revolutionary name, St. Petersburg. The move awaits legislative action.

''St. Petersburg does not sound good to my ears. I've finished Communist schools, and have never gone to church,'' Visilovsky said.

Leningrad is rich with historic sites, including the Lenin Museum, which exhibits documents and belongings to the leader of the revolution. One of 10 Rolls-Royces purchased by Lenin in 1921 is a part of the exhibit.

Near the the museum on Thursday, thousands of young people chanting ''Down with Communists'' staged a rock concert in front of Peter the Great's Winter Palace. The concert was called ''Rock Against Tanks.''

''How can rock music defeat tanks? It is impossible,'' Visilovsky said, laughing.

The balding, bespectacled veteran spoke of the coup's failure with disappointment, saying its leaders made a mistake by proclaiming emergency measures and sending tanks into the streets.

If they hadn't, he and others would have believed Gorbachev was ill, he said.

Visilovsky, who joined the Communist Party in 1941 and was decorated for his political activities, also spoke disparagingly of Russian Federation President Boris N. Yeltsin.

''Yeltsin believes in capitalism which could be deadly for socialist society. It could bring unemployment and hunger,'' Visilovsky said.

Visilovsky admitted the idea of communism is rapidly losing ground in Leningrad, as illustrated by the dwindling number of people who visit the museum.

''The number of visitors has drastically decreased in recent years, and the trend is continuing.'' said Nina Murochina, the museum's deputy director.

She complained that ''hooligans'' have vandalized exhibits in the museum, and said a replica of Lenin's dacha outside Leningrad has been burned down three times. Two days earlier, a rock was thrown through a museum window.

Because of reduced interest, the museum, now located in the beautiful Marble Palace formerly belonging to the Czar, may be moved to a less-prominent site in the city.

''The Lenin Museum will never cease to exist, because Lenin is the founder of the Soviet Union and because he is a part of our history,'' Murochina said.

But she added: ''The concept of the museum must be changed. We'll have to stop idealizing Lenin and start looking at some mistakes he obviously made.''