Metal box at the entrance to the house in Ječná street in Prague, where Hlavsa lived for most of his life and where all the important people of the "underground" culture had been meeting. If you insert a 10 crown coin into the slot, the biggest hit song of Milan Hlavsa, on YouTube, will start playing.
Milan "Mejla" Hlavsa (Prague, 6 March 1951 – 5 January 2001) was the founder, chief songwriter, and original bassist of the Czech band Plastic People of the Universe, which was part of the inspiration for the anti-establishment movement Charter 77.