Unique documents showing plans for buildings in Bristol dating back 170 years could be lost to the public if they are not digitised.
The "giant" ledgers contain designs by architects which prove the city's structures had proper sanitation.
They were created from 1851 in response to a rash of waterborne diseases.
Experts say the thin paper documents are fragile and Bristol Archives wants to scan and photograph the documents at a cost of an initial £60,000.
'DNA of Bristol'
Archivist Nicky Sugar said: "In general they're in a poor state. We do everything we can with the storage conditions, but if we can't get them digitised we will have to close them to the public.
"They represent the DNA of Bristol's built environment. As far as we know, these are quite unique.
"Although most other cities and boroughs had them, we believe only Bristol has the full run, because they were pasted into giant volumes."
Bristol Archives, which is part of Bristol City Council, now wants to raise the funds to pay for the digitisation.
It hopes to recruit a conservator and photographer to preserve the archive for future generations.