Beauly Priory dates back to the 13th Century
Historic Scotland suspects a gravestone at Beauly Priory in the Highlands was broken in a "mindless act" of vandalism.
Masonry experts from the organisation's technical conservation group will assess the damage to the stone in the grounds of the ruined church.
The priory was built for Valliscaulian monks - an order of the Catholic church - at Beauly, near Inverness, in 1230.
Part of the building was later rebuilt in the 1530s.
It is one more than 345 sites in Historic Scotland's care.
Gavin Douglas, regional works manager for the north region, said the incident was sad.
He said: "One of the historic gravestones at Beauly Priory has been damaged in what seems to have been an act of mindless vandalism.
"The individuals responsible clearly have no respect either for burial grounds or for local heritage sites which are not only assets to the community but also an important symbol of Scotland's history."