In the early 3rd century with the re-organisation of the Roman Empire, a case can be made that Lindum Colonia had become the provincial capital of Britannia Secunda and possibly a Bishop from Lincoln was present at the Council of Arles in 314 AD.

After the departure of the Romans in the 5th century Lindum declined in size and population, although archaeological evidence suggests some degree of continuity.

In the Antonine Itinerary, a road book of the mid-2nd century AD, Lindum is mentioned three times as Lindo in the Iter or routes numbered V, VI and VIII.

Then, in the Ravenna Cosmography, a listing of towns in the Roman Empire compiled in the 7th century AD, Lincoln is referred to as Lindum Colonia.

[8] The Romans conquered this part of Britain in AD 48 and shortly afterwards built a legionary fortress, possibly south of the River Witham.

This was soon replaced, around the year 60, by a second fort for the Ninth Legion, high on a hill overlooking the natural lake formed by the widening of the River Witham (the modern day Brayford Pool) and at the northern end of the Fosse Way Roman road.

[11] This was an important settlement for retired legionaries, established by the emperor Domitian within the walls and using the street grid of the hilltop fortress, with the addition of an extension of about equal area, down the hillside to the waterside below.

On the basis of Lindum's size and the patently corrupt list of British bishops who attended the 314 Council of Arles, the city is sometimes considered to have been the capital of the province of Flavia Caesariensis which was formed during the late-3rd century Diocletian Reforms.

Instead, it fits with other evidence for Lincoln retaining its central position in the post-Roman polity called *Lindēs, which became the Kingdom of Lindsey in the Anglo-Saxon period.

It was fed by the ‘‘Roaring Meg’’ spring to the North East of the city and then ran parallel with the Nettleham Road towards the N.E corner of the Upper Colonia.

The Lincoln antiquary Thomas Sympson had written in the mid 18th century, "There must have been some contrivance for raising the water a good deal above its natural level before it would run to Lindum; the spring being evidently lower than the Town: and indeed there are some traces of a Tower, or some such building at the end of the Aquaeduct by the Spring, which one may suppose would have had a reservoir on its Top."

[22] A further discovery was made in 1947 when Graham Webster excavated a kiln site producing gray ware storage jars at Swanpool, to the S.W.

Kilns producing mortaria by a potter called CATTO and also colour painted and rosette decorated pottery are known from South Carlton, to the north of Lincoln.