The discovery is being seen by scholars as one of the most important this century for Anglo-Saxon archaeology. So far, excavations have not yielded any evidence of the original fourth-century Roman church, nor of the late sixth-century rebuild. But archaeologists have unearthed parts of the foundations of four of the cathedral's Anglo-Saxon precursors, which are:
An apparently eighth-century cathedral - possible built by Canterbury's 11th archbishop, Cuthbert, who was the first archbishop to be buried there. However, so far only a small fragment of this early building has been exposed.
A probable 9th-century cathedral - perhaps built by archbishop Ceolnoth following the destruction of Canterbury by the Vikings in 850.
A 10th-century cathedral, probably built by a pagan Viking warrior's son called Oda, who became archbishop of Canterbury in 941. The discovery suggests that the church was about 200ft long and had a 79ft-wide nave.
An early-11th century cathedral, probably built by the Danish King Canute, who had conquered England. The excavations have suggested a 112ft-wide west front, with two large hexagonal towers and a great semi-circular apse.
The excavation is being directed by the archaeologist Paul Bennett, of Canterbury Archaeological Trust, in co-operation with the cathedral's own archaeological consultant, Martin Biddle, a professor at Oxford University.
Until now only the Anglo- Saxon royal capital Winchester was known to have had a vast cathedral. But the new evidence shows that Canterbury cathedral was even bigger than Winchester's and that it ranked among the top dozen ecclesiastical buildings in northern Europe.
Archaeologists suspect that traces of other massive Anglo- Saxon cathedrals may lie hidden adjacent to Norman or post-Norman cathedrals, such as Worcester, Hereford, York and Durham.