Housesteads is one of the most important forts on Hadrian's Wall. Extensive excavations were carried out between 1874 and 1981 by Newcastle University. Combining the results with those of excavations done between 1959 and 1961 by Durham University, we now have a complete plan of the north-east part of the fort. These excavations uncovered principally Buildings XIII, XIV and XV, plus stretches of rampart between the north and east gates, along with a multitude of features and stratigraphic evidence, revealing not only the sequences but also large finds assemblages. In addition to shedding much light on the material culture of the fort's occupants and the structural and chronological relationships between various parts of the fort, limited reinvestigation of Building XIV and excavation of the east end of Building XV enabled significant reinterpretation of the original conclusions reached by the Durham investigators, including some redating of structures. These excavations uncover the full 300-year period during which the fort formed an integal part of the Roman military frontier, for much if not all of that time the base of the cohors I Tungrorum milliaria peditat. This report documents the excavations and gives full finds reports, and the analysis of the evidence has enabled the authors to provide a full history of this part of the fort.