Eboracum workshops growing up outside the fortress to supply the needs of the 5,000 troops garrisoned there. Production included military pottery until the mid-3rd century, military tile kilns have been found in the Aldwark-Peasholme Green area, glassworking at Coppergate, metalworks and leatherworks producing military equipment in Tanner Row. In the Roman period, Eboracum was the major manufacturing centre for Whitby Jet. Known as "gagates" in Latin, it was used from the early 3rd century as material for jewelry and was exported from here throughout Britain and into Europe. Examples found in York take the form of rings, bracelets, necklaces, and pendants
Eboracum I came to Eboracum and, in 306, became the second Emperor to die there. His son Constantine was instantly proclaimed as successor by the troops based in the fortress. Although it took Constantine eighteen years to become sole ruler of the Empire, he may have retained an interest in Eboracum and the reconstruction of the south-west front of the fortress with polygonally-fronted interval towers and the two great corner towers, one of which (the Multangular Tower) still survives, is probably his work. In the colonia, Constantine's reign was a time of prosperity and a number of extensive stone town houses