The Stone Castle and Holbrook Cottage plaque has gone missing.
The plaque originally attached to a pedestal at the location explaining the history was removed, Sylvan Lake and District Archives office manager Christina Lust said.
"I noticed it was gone a week ago when my husband and I were out for a walk. How long it's been gone is unknown."
The Archives are also looking for 'The Ozarks' cabin sign.
"If anyone has any information, please contact us at the Archives," Lust said.
More information on the Sylvan Lake and District Archives can be found on the website, sylvanlakearchives.andornot.net, or on the Archives Facebook page.
People can also visit the Archives in person at the Municipal Government Building.
