Lancaster is one of the few cities, if not the only city, to have its Roman fort surviving as surface earthworks in the city centre. These earthworks comprise a corner of the rectangular fort, overlain with medieval defences, and they have become the subject of intense study to discover more about their character. A number of investigative projects have taken place, including the Beyond the Castle community project and the Urban Archaeological Database (UAD). These entailed a broad range of survey techniques, which have been combined together in GIS. Initially this incorporated the superimposition of records of past activity and excavations alongside historic mapping, as well as historic ground and air photographs. This was overlain with LiDAR, which provided a basic topographic model of the fort earthworks in a hillshade view. Then a photogrammetric survey was undertaken using a UAV (drone) which generated a very precise, and very detailed 3D model of the earthworks, displayed as 50mm contours. This remarkable view was further enhanced by exaggerating the vertical axis, bringing out some of the most subtle earthwork features.
A programme of geophysics was implemented using Ground Penetrating Radar (GPR) and magnetometry, which was able to separate out the Roman from the medieval earthworks. Finally an excavation was undertaken, revisiting a trench formerly excavated by Ian Richmond.
The combination of all this digital data within a GIS environment has provided an enormously valuable view of what otherwise may be perceived as just a few humps and bumps, but is allowing the piecing together of 2000 years of Lancaster’s history.