York was a huge religious center not just because of its magnificent minister, but also because it had for 450 years the largest and most important monastery of Northern England, St. Mary's. Shortly after the Norman Invasion, King William Rufus (William the Conquerer's son) founded St. Mary's in 1088. The Benedictines stayed until Henry VIII dissolved monasteries including this one in 1539. Supposedly this was a decadent place and its abbot often appeared in folklore as Robin Hood's nemesis on the Sheriff of Nottingham's days off.
In Henry VIII's day, the church had income three times
greater than that of the state. Henry was able to do a bit of wealth
transfer. Preachers went through the realm with messages that emphasized
the profligacy of the monks and promised if the king confiscated the
monasteries' wealth, the state
would never again have to tax its people. ("Read my
lips.") In short order, Henry destroyed over 800
monasteries. This was not necessarily a good thing even if he was
dissolving some pretty dissolute places. Many were far from London and
served as local centers of culture, charity, and learning.
If no longer decadent, the place is seriously decayed. Often the valuable lead would be removed from the roofs and their stones recycled in secular buildings. (This is a reverse of the early popes who took stone from Pagan buildings to create their churches in Rome).
Only the north and west wall of the abbey remains standing. See a 360-degree view from the BBC by clicking here. The Graffiti looks recent.