FLOATING MUSIC FRIDAY|A unique floating stage was installed at Slovanský Island this week, for Friday's upcoming Concert for Europe which honors the Czech presidency. For the first time in history, the Czech Philharmonic will play on the Vltava River, Ludwig van Beethoven's Ode to Joy, Smetana's Vltava, Dvořák's Carnival, and Leoš Janáček's Glagolitic Mass. The performance begins at 7 p.m.