The fate of an Edinburgh landmark will be decided by a public inquiry as co-developers Duddingston House Properties and Urbanist Hotels fight for the right to turn the site into a hotel.
The former Royal High School at Calton Hill was designed by Scottish architect Thomas Hamilton, and is considered among his finest neoclassical works.
The inquiry will weigh the co-developers proposal against that of St Mary's Music School, who was granted to develop the property in 2016.
Urbanist and Duddingston had plans to turn the site into a luxury hotel rejected by Edinburgh City Council, but have contested the decision. Meanwhile they argue that, due to an agreement with the council, the music school can not develop the site until 2022 at the earliest.
The inquiry is set to cost at least £6,000 per day.
David Orr, co-founder of Urbanist Hotels, said: "We are progressing with the appeal because we are wholly committed to bringing a world-class hotel to the Old Royal High School site in line with our contractual agreement with City of Edinburgh Council.
"We are confident that the appeals process will allow many of the complex technical issues raised with both previous planning applications to be considered thoroughly, with due consideration of the substance and detail of our proposals and the expertise of our teams.
"Put quite simply, it is the right forum to discuss such a complex and emotive issue."