Lincolnshire Police are appealing for information about a burglary at Tattershall Castle earlier this week.
Overnight between Tuesday and Wednesday (August 26-27), offenders forced open a door to a toilet block and attempted to steal a quantity of copper piping.
It is thought they may have been disturbed during the burglary, as the piping was left at the scene.
Anyone with information should contact PC Eldridge by dialling 101 and quote incident number 101 of August 27.
Report crimes anonymously by contacting Crimestoppers on 0800 555 111.