Milecastle 77 (Raven Bank) was one of a series of Milecastles or small fortlets built at intervals of approximately one Roman mile along Hadrian’s Wall. The mile fort was probably northeast of the town of Glasson, about 50 yards south of the junction of the Glasson Strait with the Strait of Bowness-on-Solway and Carlisle. Its exact location is not known. In the area in question, an excavation was carried out in 1973 by Dorothy Charlesworth, but it did not produce any useful results. Only remnants of the moat have survived southwest of the mile fort.