Excavations on the site of a rectangular earthwork at Bryn Eryr, Angelsey, have identified a sequence of occupation. In the Middle Iron Age a single clay-walled round-house stood within a timber stockade. By the later Iron Age a second house had been added, adjacent to the first, and these two houses became the focus of a planned settlement. A rectangular bank and ditch enclosure was established of 0.3 ha internal area. A yard developed in front of the houses, at the head of a trackway leading from the entrance. Rectangular post-built structures, perhaps granaries, were built and pits were dug to provide clay flooring and, perhaps, wall plastering for the houses. By the early 1st millennium AD the perimeter ditch had become choked with silt and the bank was eroding badly. A third house, with stone footings, was added to the south of the original two, one of which was by now out of use. Romano-British pottery, in small quantities but of good quality, was in use on the site. The farm appears to have been abandoned, after perhaps 700 years of development, during the late 3rd or 4th century AD.