Infrastructure makes up a considerable portion of the material culture that archaeologists study. Whether measured in terms of spatial extension or just sheer mass, infrastructural entities are often among the biggest artifacts that archaeologists encounter in the field. Yet there is no overarching theoretical framework for the archaeological study of infrastructure, and its different varieties tend to be treated in a rather piecemeal fashion. This article therefore seeks to lay some foundations for a more theoretically unified approach to infrastructure within the discipline. It offers a general definition or infrastructure, as well as a basic typology. The typology presented is fourfold, encompassing 1) static infrastructure (e.g. terraces, harbors and storehouses), 2) circulatory infrastructure (e.g. highways, canals, aqueducts and sewers), 3) bounding infrastructure (e.g. palisades, ditches and corrals) and 4) signaling infrastructure (e.g. lighthouses and beacons). By analogy with more heavily theorized categories such as urbanism, it is suggested that infrastructure should be a topic of global comparative analysis within archaeology and its allied disciplines.