Speaking to the BBC, Professor Alan Dunlop thinks the “Celtic bridge” would cost about £15bn, a fraction of the estimate of £120bn for the English Channel bridge.
He said it would boost both economies and help the post-Brexit border issue.
Alan Dunlop is one of the UK’s leading architects and a Fellow of the Royal Incorporation of Architects in Scotland.
He told BBC Radio Scotland’s John Beattie Show: “It would be a wonderful thing – a connection between Scotland and Ireland.
“We share a lot of history together, similar ideals.
“The business potential is exceptional, the chance of actually really making an investment in what would would be the true north.
“Westminster politicians talk about the northern powerhouse, but they’re really only talking about Manchester, Liverpool, Sheffield.
“This would be an investment in what would be, I think, the true North.”
Mr Dunlop estimated a cost of about £120bn for the English Channel bridge.
He continued: “The challenges of it are much less than Boris’ idea of building across the English Channel.
“We don’t have the weather problems and it is a not as significant or as large a shipping lane.
“The possibilities of it are great.
“It would send out a dramatic marker in aspiration for the country going into the 21st Century.”
Foreign Secretary Boris Johnson had suggested the channel bridge as it was announced Britain and France were investigating joint infrastructure projects.
There are two potential routes for a Scotland – Northern Ireland bridge.
“There are two ways it could go,” Professor Dunlop said. “It could go from Portpatrick to Bangor or Larne, but there are significant environmental and geological challenges there.
“We do have incredibly talented architects and engineers in Scotland so I am sure that as a technical challenge it wouldn’t be insurmountable.
“The shorter route would be from around Campbeltown, the Mull of Kintyre across to the Antrim coast.
“But getting to Campbeltown from the central belt is very difficult.”
The idea is still that – an idea – but Professor Dunlop sees it as a feasible project.
“It would be something we could debate around Brexit,” he said.
“Engineering-wise and architecturally this could be an investment in the infrastructure of Scotland and Northern Ireland.”
Economically though, the argument for the bridge may not stack up.
Economist George Kervan said the idea of a bridge between Scotland and Northern Ireland was not new, and that cost could prevent it becoming a reality.
“Big infrastructure projects can be transformative,” he said.
“But the trouble with this one is just the costs will kill it.
“A bridge from Portpatrick would be about 21 miles – that is not really effective road transport.
“You’d probably need a tunnel if you want the connection but the geology doesn’t really work there.
“And £15bn – I can think of a lot of other things to do with that.”
