Cast iron items, including skillets and flat irons, were stolen from the sod cottage at Lovells Flat.
South Otago Historical Society committee member Ian Richardson made the discovery when he went to mow lawns on Monday.
He confirmed the thieves cut a large hole in the security grille inside the cottage and went after the heavier items.
He has reported the incident to police.
''It was all OK when I mowed the lawns three weeks ago but ... when I went back to mow them again, I discovered someone had cut a one-metre by 600mm chunk out of the 10mm-thick steel grille and got inside the display area.
''They have stripped the chimney display areas of all the cast iron tools, black iron kettles, three-legged pots and stands, pans, skillets and two flat irons we had there.''
He expressed his disappointment and frustration in relation to the incident.
That sentiment was echoed by the president of the South Otago Museum-Historical Society, Roz McKechnie.
She was extremely annoyed someone had burgled the 161-year-old historic place.
''The hole was big enough for someone to crawl through and we are really annoyed they even took the section they cut out, because if they had left it there we could have re-welded it back in place and reopened the display area.
''Now we have had to secure the space and close the building until further notice, because of security issues and now are carefully checking the inventory to see what else was taken.
The society has been looking after the cottage since 1970 and in that time only one thing had been taken.
''The well known historical cottage is a community asset and it brings in funding for the society's museum in Balclutha,'' she added.
Sergeant Jason Ledley, of Balclutha said police were waiting on a full inventory of items stolen.
-Balclutha police on (03) 418 0203 or Crimestoppers 0800 555-111.
