In this talk, I will explore the connection between algebraic language theory and topos theory, focusing on why algebraic language theory is appealing to topos theorists—or at least to me. I will begin by introducing toposes as a simultaneous generalization of topological spaces and monoids. Then, I will construct the topos of automata, the topos of regular languages, and the toposes of other language classes. Finally, I will discuss what topos theory might offer to automaton theory, particularly in relation to “geometric invariants” in topos theory.