The medieval chapel of St Mary’s, at Bradwell Abbey, needs to find £50,000 to carry out the works and has launched an appeal to raise the money.
The leaks at the historical landmark are threatening the integrity of unique wall paintings dating back 600 years and the future of the medieval floor tiles.
A temporary roof has been erected at the much-loved historic monument, which is visited by people from around the country, but restoration work to secure the original roof is required.
City Mayor Debbie Brock visited the chapel on Friday to see the protective roof installed by workers.
The Milton Keynes City Discovery Centre made the unwelcome discovery while researching a new book on the chapel.
Director Henk van Aswegen said: “Ironically we had just published a new booklet celebrating this medieval gem when we found the problem.
“But we’re so glad we could do something before winter set in.
“Now we are launching a fresh appeal to businesses and philanthropists to support our restoration fund and preserve this miraculous survivor from another age.”
Sales of the illustrated booklet, ‘The Chapel of St Mary’s’, will help raise some vital funds, but more donations are needed.
The booklet is available from Bradwell Abbey, priced at £5.50, and donations can be made by calling 01908 227229.
Source: Milton Keynes Citizen