The 12th Century chapel where William Wallace is believed to have been married has been targeted by vandals.
The ruin of Old St Kentigern's Church in Lanark has become a meeting point for teenagers, with drinking, damage to gravestones and dumping of rubbish reported.
Councillor Ed Archer, an independent member of South Lanarkshire Council, called for greater security at the site and said the situation was a "disgrace".
In a report, he wrote: "Last week safety fences were in disarray and youngsters got into the restoration areas and left a trail of beer cans.
"Damage to gravestones is also on the increase.
"This is a disgrace and again it is suggested that security cameras are installed and the graveyard is locked at night."
Wallace, the Guardian of Scotland who led the defeat of the English army at the Battle of Stirling Bridge in 1297, is believed to have wed Marion Braidfute, daughter of the Earl of Lamington, at the church.
Tradition holds that Wallace also worshipped at Old St Kentigern's.