The British government has said it is seriously studying the feasibility of a bridge over the Irish Sea between Scotland and Northern Ireland, an audacious idea that has been floated by UK prime minister Boris Johnson.
Mr Johnson's spokesman, James Slack, said the proposal was being taken seriously and "a range of officials" were studying it.
"There is a proper piece of work being undertaken into this idea," he said. "The PM is ambitious in terms of infrastructure projects."
Mr Johnson has promised to build major infrastructure to better connect parts of the UK in the wake of Britain leaving the EU.
He has also vowed to boost regions outside the economically dominant south-east of England.
He has mentioned the bridge idea several times, and claimed it would "only cost about £15bn" (€17.7bn).
But engineers say spanning the deep and stormy Irish Sea would be difficult. The distance is 19km at its narrowest but one of the most likely routes, between Larne in the North and Portpatrick in Scotland, is about 45km.
However structural engineer and bridge designer Ian Firth, a fellow at the Institution of Civil Engineers, said it "ought to be possible".
He said that while there would be a "huge number of technical challenges, anything is possible if you throw enough money at it".