Edinburgh is set to have the most advanced tram system in the world, according to city transport managers.
Alstom trams are found in Dublin, Barcelona and Melbourne
The company behind the scheme has laid down its specifications to the four manufacturers vying for the £240m contract to supply 20 trams.
Each tram will be four times as long as a bus, with room for as many as 270 passengers and will travel at 43mph.
The 40m trams, the longest in the UK, will have to cope with the capital's tight curves and steep gradients.
They are scheduled to be on the streets by 2011.
Transport Initiative Edinburgh (TIE) is in charge of buying the trams and putting in the infrastructure before the whole scheme is handed over to Transport Edinburgh Limited, the new body that will eventually oversee the running of the system.
French company Alstom, Bombardier Transportation (a German arm of Canadian giant Bombardier), Spain's CAF and German-based Siemens - have three months to provide estimates and a delivery programme.
All four firms have been involved in building trams around the world, including schemes in Dublin, Nottingham and Lisbon.
Willie Gallagher, chairman of TIE, said: "The specifications that we have given to the four bidders are extremely demanding.
"Our trams will be the biggest in the UK at over 40 metres long and will need to negotiate tight curves and steep gradients.
"They'll also have to fit with Edinburgh itself - we're looking for a timeless and attractive appearance that will compliment the streets the trams will be travelling on.
"Edinburgh will have the most advanced tram system in the world."
David Mackay, chairman of Transport Edinburgh Limited, said: "I'm very encouraged by tie's approach to tram procurement for Edinburgh.
"Real progress is now being made and we're entering a new and exciting phase of the project."