The contest co-ordinator, the Landmark Wales partnership, believes the £18 million scheme will be the UK's largest and most ambitious public arts programme in the UK.
Three potential sites have already been earmarked for the project, which has recently been shortlisted for The Big Lottery Fund's Living Landmark.
These are: a plot in Holyhead Harbour, Anglesey; a site near the A55/A550 on the Flintshire Border; and a final site at the entrance to the Second Severn Crossing.
Each of the schemes will be given a budget of around £2 million and the competition organisers hope to pick 15 shortlisted teams.
According to the OJEU tender notice, the judges are looking for 'evident creativity, [a] track record of realised projects and a demonstrable appetite for exploring what this project could mean for Wales.'
Each of the shortlisted practices will be given a £5,000 honorarium 'to develop a costed and technically feasible design proposal.'
The deadline for expressions of interest is 8 January.
More information about the contest can be found at www.ted.europa.eu(2006/S243-260525).