First it was Berlin, now it is Prague marking the 20th anniversary of the collapse of communism in Europe.Singers serenaded some of those who played a crucial role in the so-called Velvet Revolution that transformed what was then Czechoslovakia. The current president, Vaclav Klaus, paid tribute to to his predecessor Vaclav Havel in the concert in a church in the centre of the capital. And there were video messages from the former Soviet leader Mikhail Gorbachev, German Chancellor Angela Merkel and US President Barack Obama. Havel himself hailed the role artists and performers played in supporting the Czech people in their push for democracy. The tide finally turned against communism in 1989 after a series of streets protests of the kind witnessed in Poland and the ex-East Germany in the same era.