Comics #16, September 1939.
References to Metropolis in the Arkham Series
- In Batman: Arkham Asylum, Metropolis is referred to as a place where Amadeus Arkham went to college.
- In Batman: Arkham City it is mentioned that a similar prison will soon be opening in Metropolis and Keystone City. In the Bowery a password in Riddler Trophy is "Metropolis" because it's maybe the Gotham-Metropolis monorail.
- In Batman: Arkham Knight, there are several posters around Gotham City stating "Fly to Metropolis," showing a red streak traveling across the sky, yet another hint at Superman.