A service is being held at York Minster on Thursday to mark the completion of a decade-long project to restore the country's largest expanse of medieval stained glass.
A special Choral Evensong service and reception will take place in the gothic cathedral's Nave to commemorate the end of the work on the Great East Window, and to thank those who were involved.
The restoration started in 2008 when the window's 311 glass panels were removed by the York Glaziers Trust, with each of them being meticulously conserved over the following ten years.
It is estimated that conservators spent about 92,400 hours on the work, part of an £11.5 million programme that has seen the Minster's stonemasons repair and replace hundreds of stones at the East End.
The conservation also saw the use of pioneering technology when, in 2014, York Minster became the first building in the country to use UV resistant external glazing to protect the stained glass, a spokesman said.
Describing the end result as "breathtaking", the Dean of York, the Very Rev Vivienne Faull, said: "The Great East Window is one of the most magnificent pieces of medieval art ever created.
"It is an enormous privilege to experience this masterpiece in this glorious state: beautifully conserved and carefully restored for generations to come.
"We're hugely grateful to York Glaziers Trust and all the people who have been involved in this epic undertaking for all their hard work and commitment."
The window is 23.3m high and 9.5m wide, covering an area of some 194 square metres (2,088 sq ft).
It was originally completed in 1408 by master glazier John Thornton, who agreed to do the job in return for £46 in wages with a £10 bonus if he finished within three years.
Sarah Brown, the director of the York Glaziers Trust, described working on the project as a "career highlight".
She said: "There's no debate - the Great East Window is up there as an international work of art and we all feel immensely privileged to have been part of it.
"I think part of what the project has achieved is a massive increase in public awareness of the stained glass at York Minster and the treasure we hold.
"It's a very, very special collection of glass and we're hugely privileged to have it."
Work is now beginning on a 20-year, £11 million project that will see protective glazing added to each of the cathedral's 128 windows.