Here, the interface of legend and fact, see Legends of Glastonbury at http://www.archaeology.org/issues/208-1603/trenches/4172-trenches-england-glastonbury-abbey
33-35 CE -- Legend. Joseph of Arimathea, holder of the Holy Grail (do a search) founds "Christian" church at Glastonbury. Church? What institution was in effect so soon after the death? No mind.
5th Century -- Site is occupied, with "definitive proof" at the Abbey site, and this from the time of the actual King Arthur, see Legends of Glastonbury
600's -- Saxons, now Christian, conquered Somerset county. King: Ine of Wessex, who built on the Abbey site, see http://www.glastonburyabbey.com/history_archaeology.php?sid=38bbee268aa83067928b28b92614b9ff
1066 -- Norman invasion. Normans added to the existing structures at the Abbey.
1184 -- Huge fire at the Monastery, see Glastonburyabbey.com site. Monks rebuild, with some new but old-looking structures, to add to the pilgrimage value, see Legends of Glastonbury site.
1191 -- Monks at the Abbey find a log, hollow but with two bodies inside and a cross with the inscription indicating that here lie "King Arthur and his wife Guinevere."
1278 -- Edward I oversees reburial, bones said to be the royals Arthur and Guinevere
1536-1541 -- Protestant Dissolution of the Monasteries, with Glastonbury Abbey included in 1539. In 1536, there were 800 monasteries, convents, friaries, reign of Henry VIII. By 1541, none, with 10,000 religious persons displaced. See Glastonburyabbey site.
1904-1979 -- Era of 36 or so excavations, but unpublished, often misinterpreted
1950's - 1960's -- more excavations, but affirmative evidence for the royals Arthur and Guinevere are contested.