More than £300m is to be spent on the linked maternity and children's hospitals in Belfast.
The Royal is to house the city's maternity services
Health Minister Shaun Woodward has agreed £2.6m funding to design the facilities on the Royal Hospitals site.
Details of the redevelopment plans were outlined in the Royal's annual report published on Wednesday.
The chief executive of the Royal Hospitals, William McKee, said they would be some of the best facilities in the world.
The hospitals are part of a major redevelopment plan on the Royal site.
In 2003, it was announced that the Royal would be the site for centralised maternity services for the city.
A new imaging centre and central decontamination unit are already under way and Mr McKee said the green light is expected shortly for a new critical care building - housing a new A&E department.
"We continue to strive to improve the environment in which we care for patients and these funds will ensure that we get expert advice in the design and development of this building," he said.
"It is an important milestone and we are very pleased we are able to move ahead now and spend almost £3m on a detailed design for what will probably be in excess of a £350m building," he told BBC News on Wednesday.
"This modern facility will be focused on the needs of women and their children and will provide a clear clinical link right across the site - from intensive care for children to neo-natal intensive care, through to our delivery suites, gynaecology and adult intensive care."
Breda Hughes of the Royal College of Midwives said she was absolutely delighted and it had been "a long time coming".
"One of the things we most welcome about this new build is the services that will be provided for women range from the extremely low-tech service provided by the midwife... to the very high tech and specialised service where a whole team of people will be working together."
Mr Woodward said the project was very important for Belfast and Northern Ireland.
"I wish to see effective and speedy progress in the design work so building can begin as soon as possible," he said.
Work is expected to begin on the new hospitals by May 2008, with the first phase of construction due to be completed by 2014 and the entire project completed by 2017.