Two ancient human skeletons and other items also believed to be from the Iron Age were found on sites near Lincoln.
Both sets of bones were found in separate archaeological sites near Navenby, which were being prepared by Anglian Water for new large-scale water pipelines.
The skeletons have been sent for further analysis by Trent and Peak Archaeology and Oxford Archaeology East, who carried out the excavations.
Other items including parts of small buildings and fragments of pottery, also believed to be from the Iron Age, were found.
Jo Everitt, Environment and Heritage Assessor for Anglian Water, said: “We know that Iron Age communities existed in the area around Navenby, and that there is well-defined Roman history there too.
“The main Roman road running from London to Lincoln and on to York, Ermine Street, now known as High Dyke, runs parallel to the proposed Lincoln to Grantham pipeline.
“Such discoveries tell us a lot about our ancient history and how Iron Age communities experienced day to day life. They can also help enhance our understanding of the development of our regional and national heritage.”
Construction on the first section, which runs from Lincoln to Grantham, is due to begin this spring. Up to 500 kilometres of new, interconnecting pipelines are being planned.
The work at the site is part of a 25-year drive to secure water supplies across the Anglian Water region.
James Crompton, Direction of the Strategic Pipeline project for Anglian Water, said: “We recognise the immense value of finds like this and will always work with experts to handle the discoveries in an appropriate manner.
“We care about the areas in which we are working and will always be respectful of anything we find.”