The Northern Ireland Environment Agency (NIEA) has said the decision to shut Scrabo Tower was not taken lightly, after one angry MLA blasted the move.
The monument, which overlooks Newtownards and can be seen from as far away as Divis Mountain, has suffered serious water damage and has been deemed unsafe.
It is to remain shut while a repair plan is drawn up.
The Alliance Party’s Strangford MLA Kieran McCarthy yesterday declared himself “angered” by the move, saying the timing of the closure “could not be worse” because many families would have wished to visit it at Easter.
“If repairs had to be made, then surely the NIEA could have waited until the winter months when the tower was closed to fix any damage,” he said.
“Safety must be paramount at all times and those in authority must ensure that there is no danger to the public, but let’s keep Scrabo Tower open.”
It is usually open at limited times during the winter months, and then opening hours increase from Easter.
An emergency decision to shut it was taken in February when problems were first discovered with the electrics.
Experts were assessing it, and this week the NIEA confirmed it is to stay closed for the foreseeable future.
It said the closure “is not a decision that has been taken lightly” – but that safety of visitors was a priority.
It offered no timeframe for when all the necessary repair work will be completed, although it added that the tower may be able to open for “special occasions”.
It said that despite spending hundreds of thousands of pounds over the last 30 years, the structure continues to let in a lot of water, adding that this is the second set of electrical problems in five years.
“This water ingress has also resulted in extremely damp and slippery conditions within the tower and in particular on the internal stairwell,” it said,
“Without lighting and due to the slippery conditions the safety of visitors to the tower would be compromised.”