As part of a project on the origin of subdivided fields in Western Sweden some surprisingly old planned fields have been investigated in the southern parts of the province of Västergötland. A type of large fossilised field consisting of long strips bounded by banks of stone and earth was found while searching for partially deserted medieval sub-divided fields. The breadth of the strips varies from approximately 7 to 40 metres. To judge from the remaining evidence, the fields often covered areas of over 50 hectares. The spatial relationship between the fields and other ancient monuments points to a date in the last centuries B.C. This dating has also been confirmed by radio-carbon datings from field boundaries, indicating a use in the period 500 B.C. to A.D. 200. The layout of the strips follows geometrical principles rather than the terrain and gives the impression of deliberate planning according to some yet unknown principle. Some of the localities consist of broad strips which have functioned as frameworks within which subdivision into property and/or working plots has later been developed. This land division seems mainly to have its origin in the need to regulate the rights to land. Strips are often too broad to have been working plots and they lack any sign of traction implements. All evidence so far points to collectively organised, subdivided field systems which have many traits in common with the medieval open fields. A metrological analysis shows that the fields were planned, measured and subsequently subdivided. The finds raise principal questions concerning the origin of subdivided fields and of individual and collective rights in the landscape. Two directions for discussion emerge. One concerns the antecedent forms in the landscape and the circumstances under which these land divisions were carried out, the other concerns the principal relations between these field systems and later subdivided fields.