Plans to convert the Ritz at Leura into a high-end nursing home will be debated in the Land and Environment Court from November 22.
A three-day hearing will begin with an on-site sitting, after a failed conciliation conference between the owners, Skermanic Pty Ltd, and council earlier this year.
Skermanic has appealed against a decision by a local planning panel to refuse its $40 million development application because a proposed new three-storey building fronting Wascoe St was too bulky.
The panel also said the proposal had "overall merit", noting the ever-increasing need for nursing home beds in the Mountains and said if concerns over the new building were addressed, an amended DA would likely be approved.
Local residents who made submissions on the DA have been invited to address the court on-site, with the National Trust Blue Mountains branch chairman, Rod Stowe, one of those who has applied to speak on Wednesday.
Mr Stowe has also written to Skermanic, expressing the branch's concerns that the buildings are deteriorating.
In particular, he noted damage to the original 1892 building. Mr Stowe took photographs in 2020 and again last month which clearly show broken weatherboards around a dormer window, exposing the wooden frame to the elements.
He also pointed out vandalism to the former manager's cottage, which faces Megalong Street. He has seen evidence of broken windows and graffiti painted on walls.
Mr Stowe said while the branch was aware of the protracted review of the project and litigation in the court, it remained concerned about continuing damage to heritage items.
"Indeed, it would appear that very little conservation or maintenance work has been undertaken on these highly significant heritage buildings since Pathways Residences assumed responsibility for the site."
He called on the company to immediately undertake essential building conservation works, irrespective of the current state of plans for the long term development of the site.
A Pathway Residences spokesperson said: "The entire project team are working extremely hard to resolve the final outstanding matters through the court process.
"Conservation works require development consent and we look forward to being able to deliver an outstanding project if the Land and Environment Court upholds our appeal.
"If approved we are very excited to have the opportunity to bring Pathways Residences quality care and accommodation to the Blue Mountains community."
