A few remnants of the presence of prehistoric people have been found in Thornborough parish. The earliest may be a ring-ditch, often the ploughed out remains of a Neolithic or Bronze Age barrow, seen in an aerial photograph near the old mill buildings. On field-walking the field a Stone Age flint scraper was discovered. There seem to be a few hints of a Late Iron Age presence with a track found in excavation near the Roman barrows, a pit cut into the side of the bank of the River Twin and some Iron Age pottery found to the south of the barrows. A cropmark near Shelspit Farm showing a large enclosure or field boundary could be prehistoric but dating is uncertain.
There is a great deal of evidence from the Roman period. The most obvious remains are the two barrows off the A421. These were partly excavated in the nineteenth century and a second century cremation burial was discovered. The possibility of a third barrow is unlikely when the aerial photographs are inspected. Excavation, watching briefs and geophysical survey near the barrows has revealed the Roman road, ford, house platforms, ditches, gullies, a cremation cemetery and lots of pottery. Some ground works by the River Board dug through a Roman floor and revealed Roman pottery in the same field as the barrows and field-walking to the south revealed Roman pottery and tile. Another Roman road was found in excavation at Brightmoor Farm. It is known that three Roman roads passed through the parish in total.
St Mary's church is the oldest building still standing in the parish, dating back to the twelfth century, with a thirteenth century chancel and north aisle, fifteenth century tower and eighteenth to nineteenth century restoration during which medieval floor tiles appear to have been mounted on the wall. The Old Manor House is also of some age, with the main hall being a cruck-built fourteenth to fifteenth century construction. Later in the sixteenth century wings were added and a linking range has been built in the twentieth century. There are fourteenth century records of the manor having a dovecote, bakehouse and animal byre. The bridge over the River Twin near the Roman barrows is of fourteenth century construction but now has an eighteenth century casing. Parts of Lower End Farm may date back to the fifteenth century but there were additions in the late sixteenth to early seventeenth century. There are earthworks of a deserted medieval settlement around Western Green Farm, comprising fishponds, enclosures, trackways and ridge and furrow but this is much damaged by recent quarrying and ploughing. There is also a platform that may have held a medieval chantry chapel for which there are historical records. There are other records that document the presence of a chapel in the thirteenth century in Barton’s Manor, and thirteenth century watermill which also possible acted as a boundary marker for the parish in the thirteenth century.
Many buildings survive from the later seventeenth, eighteenth and nineteenth centuries such as barns, houses and inns, some of the timber-framed. There was a pair of stocks on the village green that probably dated back to the seventeenth century but they were removed in the 1930s. The garden walls of the manor house date to the eighteenth century, whereas those at The Croft date to the nineteenth. A number of industrial buildings survive as well, such as the nineteenth century lime kilns and brick and tile-works at the Coombs and the seventeenth to eighteenth century mill-house with it’s leat, pond and eel trap. The waterwheel itself was dismantled in 1940 for the war effort. The seventeenth to nineteenth century windmill was partially surviving in the early twentieth century and now a mound is the only remnant. The eighteenth to nineteenth century Grand Junction Canal and Hyde Lane Lock brought changes in transport to the parish as well. Agricultural buildings were still important, however, as the nineteenth century animal pound near the manor house attests. Other changes in the nineteenth century are reflected at Chapel Cottage, which was once the Wesleyan Methodist Chapel for the parish but is now a house.