The Early Iron Age enclosures and associated sites on Sutton Common on the western edge of the Humberhead Levels contain an exceptional variety of archaeological data of importance not only to the region but for the study of later prehistory in the British Isles. Few other later prehistoric British sites outside the East Anglian fens and the Somerset Levels have thus far produced the quantity and quality of organically preserved archaeological materials that have been found, despite the small scale of the investigations to date. The excavations have provided an opportunity to integrate a variety of environmental analyses, of wood, pollen, beetles, waterlogged and carbonised plant remains, and of soil micromorphology, to address archaeological questions about the character, use, and environment of this Early Iron Age marsh fort. The site is comprised of a timber palisaded enclosure and a succeeding multivallate enclosure linked to a smaller enclosure by a timber alignment across a palaeochannel, with associated finds ranging in date from the Middle Bronze Age to the Roman and medieval periods. Among the four adjacent archaeological sites is an Early Mesolithic occupation site, also with organic preservation, and there is a Late Neolithic site beneath the large enclosure. Desiccation throughout the common is leading to the damage and loss of wooden and organic remains. It is hoped that the publication of these results, of investigations between 1987 and 1993, will lead to a fuller investigation taking place.