As autumn deepens in Seoul, the Han River will become an open-air concert hall Saturday, with four musical acts bringing classical, jazz and popular music to Yeouido for a free evening performance against the city's illuminated skyline. The Seoul Metropolitan Government said Tuesday it will host Autumn Night on the Han River, Filled With Music at Yeouido Mulbit Stage in Yeouido Hangang Park, beginning 5 p.m. this Saturday. The approximately two-hour program will feature four acts: singer Choi Seung-yeol and Kim Chang-ki of the band Zoo, jazz duo Park Jeong-in and Lee Gyu-ri, vibraphone player Yoon Hyun-sang and string quartet Ensemble Allegri. Choi gained attention as a runner-up on the second season of the television program "Hidden Singer," where he performed songs by the late singer Kim Kwang-seok. Kim Chang-ki, a singer and songwriter who performed with Kim Kwang-seok in Zoo, wrote popular songs including "On the Street" and "I'll Love You." Park and Lee will offer jazz performances, while Yoon will move between classical, jazz and pop through vibraphone arrangements. Ensemble Allegri,