Five millstones worth hundreds of pounds each have been stolen from the historic Jill windmill, just north of Brighton.
The stones weigh around half a tonne each and it's believed they were taken sometime in the last week.
It's thought it would have taken four to six people to manhandle them off the site in Clayton, possibly in the daytime as doing so in the dark could have proved too dangerous.
The 19th century corn windmill sits atop the South Downs with nearby Jack.
More top news
Becoming brighter with warm sunny spells developing this afternoon but also the risk of heavy showers
Becoming brighter with warm sunny spells but also the risk of heavy showers
Saturday morning's weather for the east of the region