Caldeum is the principal city and setting for Diablo III’s second act.
Act II moves the story from the ruined lands around New Tristram to the desert region of Kehjistan and the imperial city of Caldeum. The city’s palace, markets, sewers, and surrounding desert become major locations as the player investigates political danger and demonic activity.
Caldeum can be confused with Westmarch, which is central to Reaper of Souls, or with New Tristram, which anchors the first act. It is also distinct from Kyovashad, a major city in Diablo IV. These cities belong to different games or campaign sections even though they all function as hubs.
Caldeum’s appearance reflects Diablo III’s broader world design, moving beyond the gothic wilderness associated with the first game and presenting a large urban center shaped by desert trade and imperial power.