A statue of Robert the Bruce at the Battle of Bannockburn site has been sprawled with graffiti.
The monument, which depicts Robert the Bruce holding an axe on his horse, was spray-painted with the words “racist king”.
Pictures also show the letters “BLM” at the foot of the statue, with “Black Lives Matter” on the ground in front of it.
Police are investigating the vandalism, which they were informed about on Friday.
A spokeswoman said: “We were made aware on Friday, June 12, of vandalism to the Battle of Bannockburn heritage site, near Stirling. Enquiries are ongoing.”
The National Trust for Scotland expressed its disappointment over the incident, which it said had happened “at a time when our charity is suffering serious financial hardship”.
Stuart Maxwell, the trust’s general manager for Edinburgh and East, said: “We are very disappointed by the vandalism of the iconic Bruce statue at Bannockburn and the A-listed rotunda.
“This comes at a time when our charity is suffering serious financial hardship and this is a cost we could do without.
“We would like to thank the local community for their support in responding so quickly to this incident. A contractor will visit the site this afternoon.”
On Thursday, police said they were aware of a “small number” of Scottish statues being damaged and confirmed all recent “criminal” acts of vandalism would be fully investigated.
Assistant chief constable Kenny MacDonald also added that officers would be patrolling around these monuments in a bid to prevent any further damage.
He said: “I am aware that vandalism of a small number of monuments and statues has taken place in recent days. Such action is criminal and will be fully investigated.
“Police officers will be providing additional patrolling around such monuments and statues in the coming days to deter such criminality.
“We understand that people want to make their voices heard, but they must do so lawfully and peacefully.”