The subway station outside City Hall in 1926 New York was decorated in an ornate Art Deco style and functioned as a base for Obscurial Credence Barebone, who lurked there before attacking the No-Maj Senator Shaw. It was also the location of the epic final battle against Barebone (WFT).
Just as Newt Scamander arrived in New York City in 1926, there were reports of buildings destroyed by a mysterious force near the City Hall subway station . Percival Graves and other Aurors arrived on the scene to take testimony and were told reports of human eyes inside a "dark mass" that went underground to hide (WFT).
One night after Credence had been called a "freak" by Senator Shaw, once again his Obscurus form rose out of the same subway station to appear at a party for Shaw being held at the "ornately decorated" banquet room inside City Hall. The beastly form of Credence Barebone destroyed the hall as he hurtled towards Senator Shaw and killed him before disappearing underground again. His brother Langdon Shaw believed it was the work of witches (WFT).
Auror Percival Graves believed that it was not Credence but his young sister Modesty who was the Obscurial. He called Credence a Squib and told him he was never magical in spite of his birth mother being a witch. Goaded into a frenzy, Credence let his Obscurus take over and attacked Graves through the city, ending up at the City Hall subway station again. Aurors created a Magical Barrier Energy Field around the station entrance while Newt Scamander approached Credence on the train tracks, trying to persuade him gently to calm down and stop the violence.
But Graves, who was actually criminal Gellert Grindelwald in disguise, attacked Newt with a series of spells causing Credence to flee, right into the path of a speeding subway train. Graves/Grindelwald knocked Credence off the tracks to save him because he valued the power of his Obscurus, which he wanted to use against the No-Majs.
Outside the station, a drunken Langdon Shaw took pictures of the Obscurus while his father, Henry Shaw Sr., approached President Picquery, furious that Credence had killed his son, Senator Shaw, and vowing to expose the magical world (WFT). Soon the energy from the battle below-ground began to destroy the safety of the magical barrier, and the spectators had to flee the area.
The duel between Graves/Grindelwald and Newt Scamander continued on the underground train tracks until Credence suddenly decided to save Newt and flew with his Obscurus towards G/G, who disapparated away from him. Credence's Obscurus began to blast through the roof of the subway station just as Tina Goldstein appeared on the tracks trying once again to appeal to his human side to calm down. Credence stopped to listen to her just as Aurors approached and began to cast spells at him to destroy the Obscurus, which finally "imploded" from a mass of dark energy to a ball of light (WFT).
All that was apparently left of the Obscurus and Credence were tatters on the subway platform that looked like black feathers. Graves/Grindelwald tried to get near them, but was disarmed by Tina Goldstein and arrested by the Aurors (WFT).
From the City Hall subway station roof, Newt released Frank the Thunderbird from his case, giving him a vial of Swooping Evil Venom to drop over New York to erase the memories of the No-Maj population (WFT).