A leading American economist has called on Glasgow and Edinburgh to operate as a single city region.
Bringing Edinburgh and Glasgow together is said to be good for both
Professor Edward Glaeser said planning regulations should be relaxed to enable more house building.
He also claimed that policy makers should recognise that cars will remain the preferred mode of transport for the majority.
Prof Glaeser is in Scotland to take part in the Allander series of seminars on the economy.
Between them, Glasgow and Edinburgh are thought to contribute more than half of Scotland's economic output.
But Prof Glaeser, from America's Harvard University, has called for radical approaches to encourage what he calls Scotland's "urban core" to become one of the great centres of the information economy.
He claimed the cities can be made more attractive to skilled workers and businesses by supplying lower cost housing, reducing congestion, cutting crime and promoting key amenities.
Living with cars
Prof Glaeser said: "In the US, great amenities attract skilled people, high levels of house building keep house prices down and good transport links support impressive growth in leading cities."
While he supported continued improvement in public transport, he said policies are needed which recognise that the majority of journeys are made by car.
These could include London-style congestion charging to control traffic levels during the rush hour.
Ron Culley, chief executive of Scottish Enterprise Glasgow, said Professor Glaeser's comments "struck a chord" with the views of his and other organisations that the cities must combine to produce "strong economic growth".
There were two principle issues to tackle - the retention of skilled workers and the extension of economic progress and new jobs to areas where low skills and long-term unemployment remained a serious problem.
Edinburgh Castle, an icon of Scotland's capital
"Glasgow and Edinburgh councils and SE Glasgow & Edinburgh and Lothian have been considering this situation and talking about a series of instances where working together would be beneficial for both cities and the Scottish economy as a whole," Mr Culley went on.
"We have also jointly commissioned research on a series of practical steps which might be taken in this area.
"Both cities are dynamic, ambitious and prepared to tackle and overcome the barriers to success and there is no doubt that we will be working ever closer together in future."