the formation of the two major societies and, eventually, excavation of tunnels across several sites. In 1995 a geology student from Liverpool University carried out a micro-gravity survey of the site. Some of his findings were ambiguous, perhaps due to rubble infill, and not all of them seemed to correspond with those of the Forces Association's 1907 map. Later that year a professional firm, Parkman, carried out a survey on behalf of the Joseph Williamson Society. Both societies eventually acquired the rights to begin digging, and over time a considerable portion of Williamson's legacy has been rediscovered and cleared of the last two centuries' accumulated spoil and rubble. In the course of excavation, a substantial number of artefacts have been found - some dating back as far as the 1830s - including bottles, plates and other crockery, pipes, vintage signs, military items and other items, much of which was probably refuse dumped in the tunnels. Many of these finds have been cleaned and put on display. Extent of the excavations { "type": "FeatureCollection", "features": [ { "type": "Feature", "properties": { "name": "Friends Of Williamson's Tunnels - Mason St" }, "geometry": { "type": "Point", "coordinates": [ -2.9581868648529057, 53.40498770289791 ] } }, { "type": "Feature", "properties": { "name": "Williamson Tunnels Heritage Centre" }, "geometry": { "type": "Point", "coordinates": [ -2.9587447643280034, 53.40397711513594 ] } }, { "type": "Feature", "properties": { "name": "Friends Of Williamson's Tunnels - Paddington" }, "geometry": { "type": "Point", "coordinates": [ -2.9573124647140503, 53.40619174210474 ] } } ] }The known tunnels are in an area to the east of the Roman Catholic Liverpool Metropolitan Cathedral in a rectangle bordered by Mason Street, Grinfield Street, Smithdown Lane and Paddington. Their full extent is unknown and many are still blocked by rubble. They encompass a range of designs and sizes, from vast chambers to spaces inaccessible by an average human. The "Banqueting Hall" is around long and up to high, while the largest "Paddington" chamber is shorter but an impressive deep. Still larger excavations, such as the vaulted "Great Tunnel" seen by James Stonehouse and Charles Hand and noted on the Army surveys, have yet to be rediscovered. Purpose of the tunnels The purpose of the excavations has been the subject of widespread speculation. According to Stonehouse's near-contemporary account, Williamson was secretive about his motives, leading to a great deal of speculative local folklore. Upon hearing that Stonehouse planned to publish his research