BTS will be extending its comeback celebrations beyond the stage and into Seoul itself as it transforms the city into a massive, immersive cultural venue this spring. “BTS The City Arirang Seoul,” launching March 20 and running through April 12, is a citywide project marking the release of BTS' fifth album “Arirang,” agency Big Hit Music announced Thursday. The event will also follow the group's comeback show, “BTS Comeback Live: Arirang,” set for Gwanghwamun Square in central Seoul. “In collabo