The contemporary circus festival Letní Letná 2017 takes place from Aug. 17 to. Sept 3 in Letná Park. The 13th year of the festival that celebrates new circus, theater, music and visual arts brings top performing groups from all around the world. This year the main show will be Barbu, a brand new act by Canadian group Cirque Alfonse, who gained international praise with their hit Timber.