Contractors have begun assessing planned ground works at Casement Park ahead of the long-delayed redevelopment of the stadium.
The maintenance and pre-enabling works will run until April, when the demolition of the existing terraces will begin.
The GAA is undertaking the initial phase of works amid continued uncertainty over the funding of the redevelopment.
The stadium in west Belfast has been earmarked for matches at the Euro 2028 football tournament and will need to be completed well in advance of that event to be rubberstamped as an approved venue.
Last week Stormont’s new Communities Minister Gordon Lyons said funding remained a “big difficulty”.
Mr Lyons said the final cost of revamping the GAA stadium has not been finalised, but would be considerably more than originally envisaged in 2011.
European football’s governing body Uefa confirmed last year that the UK and Ireland will jointly host the Euros.
As part of the successful bid, Casement Park was listed as one of the stadiums where games will be played.
But the site is derelict and plans by the GAA to redevelop it with a 34,000 capacity have been mired in controversy and hit by delays.
The project has been delayed by a series of legal challenges and was further complicated by the lack of a functioning Executive at Stormont for two years.
The redevelopment has also been hit by rising costs, with an original projected price tag of £77.5 million now believed to have spiralled well above £100 million.
The GAA is part-funding the project but has yet to reach an agreement with Stormont on how to cover the multimillion-pound shortfall. The UK and Irish Governments have indicated they are prepared to offer additional funding.
Mr Lyons has said there is still no clarity on additional funding being offered from Dublin or Westminster.
Asked if the stadium would be built in time for the Euros, Mr Lyons said last week that was “entirely dependent on the funding envelope being made available”.
Ulster GAA has written to residents living close to the stadium and updated the local voluntary, business and tourism community on the pre-enabling plans and the project timeline.
