Ben Affleck's Solo Batman Rumoured to Be Set in Arkham Asylum
Reports from a few months ago suggested that Ben Affleck's solo Batman will face off against a huge number of rogues gallery members, so the latest rumour isn't all that surprising, and is in line with both those reports and the recently ended Arkham video game franchise.
Reports are that the film will center on Arkham Asylum, the home for the criminally insane that's comically bad at keeping its lunatics in-house. The Asylum is a famous locale in the Batman mythos, and is where Harley Quinn experiences her own origin (which we'll see in Suicide Squad).
With Affleck on the record stating that the film will be original and will pull from various comic book sources, Batman On Film, who come with the report, suggest one such source would be Arkham Asylum: A Serious House on a Serious Earth.
With Lex Luthor being personally moved to Arkham Asylum by Batman at the end of Batman v Superman, it's very likely that the hospital will play an integral part in some way or another in the DCEU.
Source: Comicbook