Lasers are being used to create a three-dimensional image of Lincoln Cathedral so it can be recorded in exact detail.
The survey will monitor the cathedral's 'sway'
Church authorities say most major buildings have not been drawn properly and in the event of a disaster would be very difficult to reconstruct.
The laser takes up to 3,000 measurements a second.
It will also provide "virtual" tours for people who cannot reach parts of the cathedral in person.
Phillip Dixon, a consultant archaeologist working on the project, said: "After the fire at York Minster, despite having many drawings and photographs, they found that wasn't enough information to recreate what was lost without some second guessing.
"We want to do the work before any disaster happens - after all Lincoln has had one earthquake, two or three fires and several lightening strikes that I can remember."
Once a map of the cathedral has been made, it will be combined with photographs to create computer tours of areas not accessible to those with mobility problems.
Mr Dixon also said the survey would help in the day-to-day maintenance of the cathedral, checking movement in the structure and to determine how far it swayed in the wind.