Gambling dens (synonyms: betting houses, casinos; example toponyms: Madam Dorsey’s) are locations where betting occurs (either legally or illegally). They are usually found in towns or cities and may be located in a secret club. In narrative worlds, gambling dens, and betting, may be used as a means for a protagonist to win a valued prize or extract useful information. In game worlds, a gambling den is often the site of minigames, many of which may be entirely fictional games unique to that world.

When designing a gambling den, first consider what is being bet on: a fight, a card game, a dice game, a race, or something else?