The cultural and visitor centre at Padraig Pearse’s cottage in Rosmuc in Connemara will not be completed in time for the 1916 commemorations.
The centre is one of eight flagship capital projects, which form a core part of the State's 2016 Centenary programme.
Údarás na Gaeltachta, which is overseeing the Pearse project, has confirmed that the development will not be completed until the end of September.
Preparation work has been carried out on the site and it is expected that construction work will start next week.
The Údarás also said it hoped that a walkway, Slí na Coille - which is one part of the overall project close to Pearse's cottage - would be open by Easter.
The cottage in Rosmuc in Connemara is where Pearse, one of the leaders of the 1916 Rising, spent his summers from 1909 to 1915.