''Animafest'', the World Festival of Animated Films, takes place every even-numbered year, and the ''Music Biennale'', the international festival of avant-garde music, every odd-numbered year. It also hosts the annual ''ZagrebDox'' documentary film festival. The ''Festival of the Zagreb Philharmonic'' and the flowers exhibition ''Floraart'' (end of May or beginning of June), the ''Old-timer Rally'' annual events. In the summer, theatre performances and concerts, mostly in the Upper Town, are organized either indoors or outdoors. The stage on Opatovina hosts the ''Zagreb Histrionic Summer'' theatre events.