Iceberg Lounge safe code location in Lego Batman: Legacy of the Dark Knight

In Chapter 1 of Lego Batman: Legacy of the Dark Knight, you can find the Iceberg Lounge safe in the VIP area.

Collect the two paper clues there, combine them, and use the code 596 to open the vault.

Inside is a red brick, a valuable collectible that unlocks a cosmetic modifier like the Filthy Rich reward.