Glastonbury Tor is a hill in Glastonbury, Somerset, England, which features the roofless St Michael’s Tower and forms an iconic part of the local landscape.

Tor is a local word of Celtic origin meaning "rock outcropping" or "hill". The Tor has a striking location in the middle of the Summerland Meadows, part of the Somerset Levels. The plain is actually reclaimed fenland out of which the Tor once rose as an island but now, with the surrounding flats, is a peninsula washed on three sides by the River Brue. The remains of Glastonbury Lake Village nearby were identified in 1892, showing that there was an Iron Age settlement about 300–200 BC on what was an easily defended island in the fens. Earthworks and Roman remains prove later occupation. The spot seems to have been called Ynys yr Afalon (meaning "The Isle of Avalon") by the Britons and is believed by some to be the Avalon of Arthurian legend.

A model of Glastonbury Tor was incorporated into the opening ceremony of the 2012 Summer Olympics in London. As the athletes entered the stadium, their flags were displayed on the terraces of the model.

Some Neolithic flint tools recovered from the top of the Tor show that the site has been visited and perhaps occupied throughout human prehistory. Excavations on Glastonbury Tor, undertaken by a team led by Philip Rahtz between 1964 and 1966, revealed evidence of Dark Age occupation around the later medieval church of St. Michael: postholes, two hearths including a metalworker’s forge, two burials oriented north-south (thus unlikely to be Christian), fragments of 6th century Mediterranean amphorae (vases for wine or cooking oil), and a worn hollow bronze head which may have topped a Saxon staff. The Celtic name of the Tor was Ynys Wydryn, or sometimes Ynys Gutrin, meaning "Isle of Glass". At this time the plain was flooded, the isle becoming a peninsula at low tide.

Remains of a 5th-century fort have been found on the Tor. This was replaced by the medieval St. Michael’s church that remained until 1275. According to the British Geological Survey, an earthquake was recorded on 11 September 1275, which was felt in London, Canterbury and Wales, and this quake destroyed the church. The quake was also reported to have destroyed many houses and churches in England, suggesting intensities greater than 7 MSK and an epicentre in the area around Portsmouth or Chichester, South England. It is possible that the shape of the tor led to a local amplification of the seismic waves where the church was situated.

A second church, built in the 1360s, survived until the Dissolution of the Monasteries in 1539 when the Tor was the place of execution where Richard Whiting, the last Abbot of Glastonbury Abbey, was hanged, drawn and quartered along with two of his monks : John Thorne and Roger James. The remains of St. Michael’s Tower were restored in modern times. It is a grade I listed building and is managed by the National Trust.

The site of the fair held at the foot of the Tor is embodied in the traditional name of "Fair Field" given to an agricultural enclosure, the enclosures in the local landscape dating from the 18th century.

The Tor has been associated with the name Avalon, and identified with King Arthur, since the alleged discovery of King Arthur and Queen Guinevere’s neatly labelled coffins in 1191, recounted by Gerald of Wales. Modern archaeology has revealed several sub-Roman structures.

With the 19th-century resurgence of interest in Celtic mythology, the Tor became associated with Gwyn ap Nudd, who was first Lord of the Underworld, and later King of the Fairies. The Tor came to be represented as an entrance to Annwn or Avalon, the land of the fairies.

A persistent myth of more modern origin is that of the Glastonbury Zodiac, an astrological zodiac of gargantuan proportions said to have been carved into the land along ancient hedgerows and trackways. The theory was first put forward in 1927 by Katherine Maltwood, an artist with an interest in the occult, who thought the zodiac was constructed approximately 5,000 years ago. However, the vast majority of the land said to be covered by the zodiac was under several feet of water at the proposed time of its construction.

Christopher Hodapp asserts in his book The Templar Code For Dummies that Glastonbury Tor is one of the possible locations of the Holy Grail. This is because it is close to the location of the monastery that housed the Nanteos Cup.

Another speculation is that the Tor was reshaped into a spiral maze for use in religious ritual, incorporating the myth that the Tor was the location of the underworld king’s spiral castle.

Холм святого Михаила - естественное возвышение высотой 145 метров, над которым вздымается средневековая башня церкви св. Михаила, повреждённой землетрясением 11 сентября 1275 года.

Церковь была упразднена в правление Генриха VIII, когда проводилась секуляризация монастырских владений; последний аббат Гластонберийский был повешен на этом холме в 1539 году.

Холм расположен в виде семи рукотворных уступов. Во время археологических раскопок выяснилось, что в III веке до н. э. здесь существовало значительное кельтское поселение, а в V в. н. э. — небольшая крепость. В древности во время частых наводнений холм, господствующий над окружающей болотистой местностью, превращался в малоприступный остров. Местные жители склонны толковать его уступы как древнекельтский лабиринт.

Холм св. Михаила издревле связан в народных поверьях с легендами о короле Артуре. В 1191 году монахи близлежащего Гластонберийского аббатства объявили об обнаружении ими саркофагов с именами Артура и его супруги Гвиневры. В новое время холм привлекал внимание оккультистов и исследователей паранормальных явлений, которые признают его за портал в потусторонние миры (Авалон). Холм и башня находятся под охраной государства и объявлены памятниками общенационального значения.