Proceedings of the Cambridge Antiquarian Society C pp. 99–136 Between late 2006 and the middle of 2008 archaeological excavation was carried out at ten locations along the 18 kilometre route of the Cambridgeshire Guided Busway. Monitoring of groundworks was also carried out along the whole length as well as heritage railway recording of the track and at key locations. Archaeological remains were found at seven of the excavation locations as well as in one significant location during the monitoring programme. Three of these sites are dealt with in other publications; the remainder are reported on in this paper. Two sites at Swavesey revealed evidence of Iron Age and Roman activity, extending the known area of occupation on the island at this date down to the fen-edge. The evidence suggests that this was a processing or redistribution loca- tion rather than dense settlement. At the Windmill site near Over remains of a similar period were found, but here there was clear evidence of settlement extending from the middle Iron Age through to around AD 70 when it is likely that the settlement focus shifted due to landscape reorganisation. At Arbury evidence was found indicating the presence of a substantial Roman building with finds of pottery, building material and coins. The Cambridgeshire Guided Busway (CGB) has been constructed in large part on the trackway of the former Cambridge to St Ives railway. Work began in late 2006 and as part of the programme extensive ar- chaeological work was undertaken by the Cambridge Archaeological Unit (CAU) in order to satisfy condi- tions placed on planning permission. The archaeolog- ical work was co-ordinated on behalf of the contractor BAM Nuttall by Steve Haynes of Arup (Archaeologist to the Design Joint Venture) and was monitored for Cambridgeshire County Council Archaeology Office by Andy Thomas, Senior Development Control Archaeologist. Based on the results of desktop assessment (Arup 2003) and trenched evaluation (Collins and Dickens 2009), and reflecting a number of subsequent design changes, ten locations along the CGB route were even- tually designated for mitigation by excavation or to be evaluated in order to determine mitigation. The field- work was carried out between October 2006 and July 2008, as sites were made available (Fig. 1). Specifically these were (from north to south): • Swavesey in-track site (Jun/Jul 2008) • Swavesey Kiss & Ride (Jan/Feb 2007) • Landscape and Ecological Mitigation Area (LEM) C (Apr 2007) • LEM D: The Windmill Site (Nov 2006 – Jan 2007) • Longstanton Park & Ride (Oct/Nov 2006) • LEM I (Apr 2007) • Arbury Park (Sep/Oct 2007) • Long Road Construction Site (Jan/Feb 2007) • Addenbrooke’s Link (Mar 2007) • Shelford Road Construction Site (Feb/Mar 2007) In addition to these ‘set piece’ sites, archaeologi- cal monitoring was carried out on the contractor’s groundworks along the entire length of the busway, commencing in December 2006. This included: • Monitoring of geotechnical test pits along the entire route • Monitoring of ballast stripping • Monitoring of haul road construction • Monitoring of service diversions and replacements • Monitoring of track groundworks (e.g. pad founda- tions) During monitoring archaeological remains pre-dat- ing the Post-Medieval period were observed at rela- tively few locations, the exception being at Arbury in-track (see below). As the investigations progressed little or no ar- chaeology was revealed at the LEM C, LEM I and Long Road Construction sites. Other than to record their inclusion in the project, these sites will not be dealt with further. Three other sites did have minor archaeology, but lie within the immediate vicinity of other ongoing large projects and are more properly dealt with there. These are the Longstanton Park and Ride, to be dealt with as part of the Northstowe in- vestigations, the Addenbrooke’s Link site, to be dealt with as part of the 2020 project, and the Shelford Road Construction compound, dealt with as part of the forthcoming Addenbrooke’s Link Road Publication (Timberlake forthcoming). The main focus of this paper are the four remain- ing sites: Swavesey in-track and Kiss & Ride; LEM D (the ‘Windmill’ Site) and Arbury Park and the Arbury in-track observations (Fig. 1). These are singled out Down the Line: Archaeological investigations on the route of the Cambridgeshire Guided Busway Alison Dickens and Matthew Collins With contributions by Katie Anderson, Vida Rajkovac ˇa, Anne de Vareilles, Lawrence Billington, Matthew Brudenell, Natasha Dodwell, Andy Hall, Mark Knight and Simon Timberlake