“RIVER VIEW BAR” is a rooftop bar on the 23rd floor of the Grand China Hotel. The official website describes it as follows. “Opening Hours: Everyday, 3:00 PM – Midnight” But, The entrance written “Open 16:00 - 23:00 Hrs”. Admire the impressive Bangkok nightscape and mesmerizing views of the Chao Phraya River. I think it's a hidden rooftop bar.