Dora the Explorer is a mobile robot with a sense of curiosity and a drive to explore its world. Given an incomplete tour of an indoor environment, Dora is driven by internal motivations to probe the gaps in her spatial knowledge. She actively explores regions of space which she hasn't previously visited but which she expects will lead her to further unexplored space. She will also attempt to determine the categories of rooms through active visual search for functionally important objects, and through ontology-driven inference on the results of this search. Categories and Subject Descriptors I.2 [Artificial Intelligence]: Robotics General Terms Algorithms, Experimentation Keywords cognitive robotics, motivation, exploration, mapping, reasoning