The competition - which is open to all European Union-based architects - has the full backing of the International Union of Architects.
The scheme, according to the brief, must encourage 'harmonious and sustainable development, be economically viable and provoke civic pride and community engagement'. The site attracts 400,000 visitors a year.
The winning scheme will total 1,800m2 of floor space and will include interpretation and education rooms, retail units, catering facilities, and a tourism information centre.
The international jury will include Peter Hunter from England and Aiden McGrath from Northern Ireland.