The amphitheater at the Lazienki Park serves as a venue for free Chopin concerts every Sunday afternoon. Long live the music of Frederic Chopin!
The amphitheater is somehow far from the park entrance so get ready for a long walk down. Think well too how do you intend to walk back up. Just thinking about accessibility for the mobility challenged. I saw lots of old people struggling to get to and from the amphitheater... was not easy.