Skellig Michael is to remain closed to visitors for the rest of the year due to COVID-19 restrictions.
The Office of Public Works has announced details of how it plans to reopen a variety of sites and locations over the coming weeks and months.
Many grounds and gardens will be open when 'phase one' of the Government's roadmap gets underway from Monday.
However, visitor centres, galleries and museums in many sites will be unable to reopen until phase four in late July.
Skellig Michael - which is typically only open to visitors for a limited time each year and can only be accessed by boat - is now not set to reopen by the end of the summer.
In a statement, the OPW said: “The character of the passenger journey to Skellig Michael is, in our view, highly challenging when considering COVID-19 risks.
"On a mobile, constantly-moving platform like a boat, there are multiple touch and clutch points which passengers will hold onto and of course they all need direct assistance to safely board the vessel and get off at the destination pier.
"In these circumstances, prevention of virus transmission is extremely difficult and we have concluded that it is not feasible to guarantee passenger safety.”
Other heritage sites that cannot be opened for now will be kept under constant review, the organisation noted.
The OPW also says that, from Monday, a number of its outdoor sites will have times reserved for people who have been cocooning.
Meanwhile, Wicklow County Council has confirmed Glendalough's upper car park will reopen on Monday.
The council says people are being urged to continue to follow the 5km restriction on travel, which they say will be enforced by gardaí.
The Glendalough car park was closed in March after a large amount of visitors travelled to the site during the early stages of social distancing and coronavirus restrictions.
While that site is now reopening, Wicklow County Council says the Bray to Greystones cliff walk will remain closed for now.
