The final resting place of Queen Victoria and her beloved Albert is suffering from damp.
The Royal Mausoleum at Frogmore is the responsibility of the Royal Household.
But recent monitoring revealed that an inadequate drainage system has caused a problem with damp.
Now a scheme of temporary additional rainwater drainage has been agreed with English Heritage and work is underway.
This will enable the building to dry out so that conditions can be stabilised.
The latest Heritage at Risk register, produced annually by English Heritage lists the Royal Mausoleum at Frogmore House in the Home Park as one of the country's treasured historic sites that needs attention.
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