The Taoiseach has said it was "scandalous" that Government agents got the estimates of the National Children’s Hospital project so wrong.
Speaking on Newstalk radio, Leo Vardakar said those agents made "big mistakes in calculating the costs of the hospital", but added it was money that would not be wasted.
Last month, the Oireachtas Health Committee heard that the cost of the hospital was €450m higher than the figure of €983m approved by the Government in 2017.
Mr Varadkar said he did not think that the overall costs would have been lower if things were done better.
However, he said he was in disbelief when he heard the amount of the cost overrun.
Mr Varadkar defended the location of the hospital alongside St James' Hospital and said that the value of the project should never be forgotten.
He said the hospital will transform paediatric care in Ireland.
The Taoiseach said that the Government had to learn from the mistakes made on the National Children’s Hospital before signing up to the National Broadband Plan.
Yesterday, he told the Dáil that the plan will cost "many multiples" of the original estimate.
Speaking on the same programme this morning, Mr Varadkar said the plan was a different type of public-private-partnership contract, with costs spread over 30 years.
He said a decision would be made on how to proceed by Easter.
However, Mr Varadkar warned that a no-deal Brexit scenario would require the Government to find hundreds of millions to support beef farmers and that may affect any major infrastructure projects that are planned.