There was a church here in 1055, dedicated to Saint Olaf - the Christian king of Norway who had been killed at Stiklestad in 1030 and whose cult spread through northern Europe. Saint Olaf's church in York was a small Anglo-Scandinavian foundation in a Viking-shaped city. Then the Normans arrived. After the Conquest, the church passed to Alan Rufus, the Anglo-Breton magnate who had fought at Hastings and now held vast estates across northern England. He granted the lands to Abbot Stephen and monks from Whitby. In 1088, King William II - Rufus's eponymous nephew, the second Norman king of England - visited York and refounded the abbey. The next year he laid the foundation stone of a new Norman church and rededicated it to the Virgin Mary. A great fire damaged it in 1137. The walled precinct visible today was built in the 1260s under Abbot Simon de Warwick.

At its dissolution in 1539, St Mary's was the largest and richest Benedictine establishment in northern England - worth more than £2,000 a year, one of the biggest landholders in Yorkshire. Fifty monks lived in the cloister. The abbey owned manors, mills, fisheries, churches across the region. The abbots wore mitres, ranked with bishops, and were habitually summoned to Parliament. An anonymous monk here in the late 14th century composed an Anglo-Norman chronicle that included the most detailed surviving description of a medieval English parliament and a first-hand account of the Peasants' Revolt of 1381. The men who wrote, copied, and bound these manuscripts watched the kingdom go by from the windows of the scriptorium. None of them lived to see what Henry VIII would do.

The royal commissioners came and the abbey gave up everything: £2,085 to the Crown, and fifty monks turned out into the world with small pensions. The buildings were stripped of lead, valuables, and meaning. The church was demolished or left to collapse. A 13th-century Limoges enamel figure of Christ - gilt, small enough to hold - was hidden somewhere in the abbey precinct and missed by the commissioners entirely. It was rediscovered in 1826, disappeared again, surfaced in a private German art collection in the 1920s, and was finally bought back by York Museums Trust in 2019. It is on display now in the Yorkshire Museum, a few steps from where it spent at least three of the last five centuries hidden.

What the dissolution did not destroy, the 18th century quarried. Cut stone is valuable, and the abbey ruins were treated as a free quarry. In 1705, stone was carted off to repair St Olave's Church. Between 1717 and 1720, more went to Beverley Minster, 25 miles away. In 1736, blocks were taken for the landing stage of the Lendal Ferry. By the time the Yorkshire Philosophical Society began building the Yorkshire Museum on the cloister site in 1827, much of the abbey was already gone. What survives is the north and west walls of the precinct, the timber-framed Pilgrims' Hospitium, the medieval West Gate, and the 14th-century Abbot's House - now called the King's Manor and used by the University of York. The arcade you photograph in the gardens is essentially the church's north nave wall, standing like the broken keyboard of an enormous piano.

Excavations in 2014 and 2015 found something remarkable: the medieval archaeology lay extraordinarily close to the surface, in some places only 7 centimetres below the modern lawn. An apse was found in the south transept. Wall foundations were traced. Small finds dating from Roman to modern times tumbled out of the topsoil. Fragments of human remains - disturbed burials from the abbey graveyard - were among them. Centuries of York Museum visitors had walked their dogs across the bones of buried Benedictines. The graves include Stephen, Count of Tréguier, Abbot Thomas Spofforth, and William de Vescy of Kildare. Walk the Museum Gardens today and you walk through a Benedictine community still partly there, just under your feet.