Architects have been appointed to carry-out an initial survey
Plans to modernise Bath Abbey are being closely monitored by conservationists.
The church council says the building is not fit for purpose with inadequate lighting and only one disabled toilet for a congregation of nearly 1,000.
"We need catering facilities and better choir rooms - we need to respond to what society wants now and in 50-years' time," an abbey spokesman said.
But Bath Preservation Trust says it was important the abbey look at the significance of the planned changes.
Chief executive Caroline Kay said the existing abbey was 500 years old and "in that time it has changed and adapted and we recognise that".
"We welcome people looking at historic buildings positively to give them continuing life.
"We will have to look at the historic significance of any changes they are proposing to make sure they respect the fabric and make sure they don't throw the baby away with the bathwater in order to bring it up-to-date," she added.
The church council wants to attract more people with major exhibitions and utilising the natural acoustics for concerts.
It has appointed architects to make an initial survey of the building and say there will be a period of consultation before plans are finalised.
Rector Edward Mason said the building had had a major change in virtually every century.
"The abbey has been made to fit what people want to do with it and in it.
"We want to ask ourselves what sort of heating or seating we want - we're open to ideas so we can improve on what we have got at the moment," he added.