What the Lazarus Pit is
Dennis O’Neil and Neal Adams introduced the Lazarus Pit in Batman #243 (July 1972) as the mechanism Ra’s al Ghul uses to extend his life across centuries. The framework: a chemically-and-mystically active pool that resurrects the dead and grants longevity, with the side effect of temporary madness on the resurrected. Multiple Pits exist worldwide. The mechanism has been canonical across DC publishing since 1972 and has appeared in nearly every Ra’s al Ghul-related storyline.
Collector context
Batman #243 trades in the four-figure range at CGC 9.4 and above.