This image captures a big moment: for the very first time, two Marvel heroes meet.
From Marvel Mystery Comics #8, 1940.Was this a fictional universe at all? Wasn’t that the Manhattan skyline behind the Torch? Wasn’t that the Hudson River that the Sub-Mariner was diving into? Superman and Batman had smiled together on a few carefree covers, but every kid knew that they were fully tethered to their respective Metropolis and Gotham City, and that never the twain would meet. Who cared if the Acme Skyscraper fell, or the First National Bank had to give up its cash? Timely’s New York City, on the other hand, was rife with Real Stuff to Destroy. In Marvel Mystery Comics #8 and #9, which hit newsstands in the spring of 1940, Namor wreaks havoc on the Holland Tunnel, the Empire State Building, the Bronx Zoo, and the George Washington Bridge (“Hah! Another man-made monument!” he shouts, breathlessly aroused at the potential carnage) before the Human Torch finally confronts him, and the battle rages to the Statue of Liberty and Radio City Music Hall. Was it possible that they’d turn a corner and meet the Angel? Or, better yet, show up at the reader’s home?
(Text from Marvel Comics: The Untold Story)