Background

The 80 Roman miles of Hadrian’s Wall are now split across 3 counties, numerous heritage organisations and sites, and hundreds of landowners. Information about the history and archaeology of the Wall and all its features can be found in the archives, museums, scheduled monument listings, and HERs that cover the length of the Wall, as well as over a hundred years of excavation reports, antiquarian diaries and letters, historic mapping, countless books and publications, and local knowledge. This is a vast amount of data, and more is constantly being added as further research and excavations take place. While it is fantastic that there is such a large volume of information about the Wall, it can be difficult for researchers and the public to find and access it all, as it is spread across so many different sources. One of the main outputs of the Hadrian’s Wall Community Archaeology Project (WallCAP) aimed to bring a large amount of this information together into one place with the creation of the Wall-wide GIS. The WallGIS primarily consists of an underlying geodatabase which holds descriptive information, spatial data, and many other attribute options to capture the characteristics of the Wall and its features. This geodatabase is linked to GIS files so it can be displayed in ArcGIS, QGIS or other mapping software, allowing users to run spatial analysis or create maps using the data. Each individual feature that makes up the Hadrian’s Wall monumental complex, each turret, mileacastle, fort, and linear mile of curtain, ditch, and Vallum, has a record in the WallGIS. This data can be explored via the online map and search functions on the Archaeology Data Service website. Users are also able to download the accompanying .csv and shapefiles to examine the data themselves and use it as the basis for further analysis and research.

What is GIS?

GIS stands for Geographic Information System, which is a system that allows users to create, manage, analyse, and map different types of data. Essentially, you can add many different types of data, like elevation data, aerial photos, old maps, site locations, rivers, etc to the system. Each of these is a layer, and together they create a digital representation of the real world. All the data can then be run through a variety of analysis processes and the results, or the original data, can be turned into maps and other visualisations.

Development of the WallGIS

The underlying geodatabase was custom designed and built by WallCAP staff using Microsoft Access. The database was designed with many attribute options, which allowed us to capture the varied characteristics and fine details of the Wall. The initial phase of desk based research and data collection for the database was done by WallCAP volunteers during Covid lockdowns in 2020 and 2021. A standardised data collection form was created for each feature type, and volunteers filled this in for each individual feature along the Wall. This data was then quality checked by WallCAP staff and entered into the WallGIS database. Staff also conducted further detailed research to fill in gaps in the volunteer gathered data. We also linked other related datasets, like quarry and other geological data, into the database. Finally, the WallGIS went through further quality control checks and a peer review process before being sent to the Archaeology Data Service for digital hosting and display.

Please note:

• As of September 2022, the WallCAP project has come to an end. This means that the WallGIS is no longer being regularly updated with new information and data. It is accurate to information that was available to August 2022.
• All measurements within the WallGIS database and associated shapefiles are in metres.
• If the database mentions “the Wall” with a capital W, this refers to Hadrian’s Wall. It has also been referred to as curtain wall.
• Some of the sites include TW or SW in their name, like Turret 50a TW or Milecastle 50 SW. TW is the shortened form of Turf Wall, and SW is the shortened form of Stone Wall.
• Confirmed versus Assumed sites: A Confirmed milecastle or turret site is a site that has been located by excavation, geophysical survey, or that is visible as surviving, upstanding remains or earthworks. An Assumed milecastle or turret site is a site whose location has been determined based on measurements from other known (confirmed) milecastles or turrets.
• The database requires single years for the “Start Date” and “End Date” variables, so date ranges have not been used in these categories. The dates used align with current research. These were:
• Roman ‘life-span’ of the Wall = AD 120-410
• Initial construction of the Wall = AD 120
• The 'fort decision’ and addition of the Vallum = AD 122
• Secondary forts = AD 130
• Rebuilding of the Turf Wall in stone in the Birdoswald sector = AD 130
• The associated GIS shapefiles for the features that make up Hadrian’s Wall have been made as accurately as possible, however there may be some inherent errors within the data.
• The polylines representing the linear features of Hadrian’s Wall – the Curtain Wall, the Wall Ditch, and the Vallum – are more generalised representations of these features, and are best viewed at a larger scale.
• There are two versions of the linear feature shapefiles. The WallGIS_CurtainLine, WallGIS_DitchLine, and the WallGIS_VallumLine is a simple line to show the entire feature as a whole. The WallGIS_CuratinWall_polyline, WallGIS_Ditch_polyline, and the WallGIS_Vallum_polyline files have each feature divided by Wall mile, and the associated WallGIS database information is linked to each individual mile within those features.
• For the Turret polygon shapefiles: where the exact dimensions of a turret are known, those measurements have been used to create the polygon for that site. For turrets where the location is assumed or we do not have exact measurements of the walls, a general 5m by 5m polygon has been used to represent the site.
• For the Milecastle polygon shapefiles: where the exact dimensions of a milecastle are known, those measurements have been used to create the polygon for that site. For milecastles where the location is assumed or we do not have exact dimensions, a general 20m by 20m polygon has been used to represent the site.
• Discovery Area polygon shapefiles: these Discovery Area polygons have been created at the locations of Assumed milecastles and turrets. As the locations of Assumed sites have been determined by measurements from other known Wall sites, there is the possibility that the Assumed milecastles and turrets could be located in the vicinity of the current suggested location. The Discovery Area polygons represent this potential area. For Turrets, the Discovery Area is 100m to the east and west of the current suggested location of each of the assumed Turrets. For Milecastles, the Discovery Area is 300m to the east and west of the current suggested location of each of the assumed Milecastles.
• The research used to populate the database was as comprehensive as possible, but some sources of information may have been missed.