In the late 80s or early 90s, DC put out another one of those story arcs where basically everyone in their universe was involved (a DC staple, methinks), and in this particular arc the ancient, classical deities and characters and their world was either merged with or came down the earth.
I can't remember if they were Greek gods or their Roman counterparts (or possibly both?), but I remember it was a huge crisis (duh, it's DC!) and scenarios put DC heroes in situations where they were matched up against similar deities (like Flash having to run against Hermes or Mercury).
I also can't remember if it was a massive crossover or a limited series. I do remember having several of the comics, though, and I lean towards thinking it was a mainly a limited series but ongoing titles had tangential crossover stories.
My son is really interested in mythology and comics and I think he'd dig this, so thanks in advance for any help.