Czechs and Slovaks have marked the 15th anniversary of the start of the Velvet Revolution against communist rule.
Vaclav Havel warned of continued support for communism
In the Czech capital, Prague, people on Wednesday re-enacted a 1989 student march that led to further protests and the eventual fall of the regime.
Revolution leader and former president Vaclav Havel laid a wreath at the spot where students and riot police clashed.
He warned of the communist party's continuing support in the country, saying: "It's not a good thing".
The former dissident playwright was greeted earlier by cheering crowds who chanted "Long live Havel", and "Thank You Havel".
Candles were lit and bouquets left beside grainy photographs of communist-era police in riot gear, the Associated Press news agency reported.
An outdoor concert and speeches by political leaders and former dissidents were being held in Prague during the day.
British Minister for Europe Denis MacShane was also due to open a new "speaker's corner" in Prague, modelled on the site where people freely gather for debate in London's Hyde Park.
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In neighbouring Slovakia, the anniversary was being marked by publishing the names of former secret police agents on the internet.
A commemoration event was also held in the main square of the Slovak capital, Bratislava.
The 1989 protest began with fiery speeches against the communist regime at a university campus in Prague on 17 November.
Thousands of students then marched downtown through Narodni street.
After a tense standoff with riot police, the authorities decided to break up the protest with force.
Within days the demonstrations had swelled to hundreds of thousands of people.
By the end of the year the communist party had been swept from power and Mr Havel was Czechoslovakia's elected leader.
The country's two constituent republics split in 1993.
The organisers regard the anniversary as more than an exercise in nostalgia, the BBC's Rob Cameron in Prague reports.
They say the communists are creeping back into positions of power, and critics say they have never been held properly accountable for the excesses of the past.
But some on Wednesday were staging a protest to highlight disillusionment at the current political situation, with ambivalence over EU membership and pessimism at the job situation.
"No-one wants communism back but at least we had security and enough to live on back then. There's not much reason to celebrate the end of communism," pensioner Marcela Kozerova told AFP news agency.