NYC Health + Hospitals/Metropolitan

Joker: Interior scenes appear to be filmed at Metropolitan Hospital in East Harlem, which is also shown in an aerial shot at the opening of the teaser trailer. Metropolitan Hospital’s interior hallways were also a film set for the television show New Amsterdam. Source: https://untappedcities.com/2019/09/13/see-the-nyc-filming-locations-in-joker-starring-joaquin-phoenix/