Imagine trying to renovate a 2,000-year old building and not being able to find a bricklayer.
Two thousand years of history will be visible from the north gate
The restoration of Cardiff Castle is proceeding as planned, but construction trainers who were given a guided tour of the work have warned that similar projects face a skills shortage.
Around 70 Members of the British Association of Construction Heads (BACH), which is holding its annual conference in Cardiff, became the first group to tour areas of the castle which will become accessible to the public for the first time when work is completed in 2008.
The behind-the-scenes tour was intended to show educators the kind of skills now needed by the students before they enter the construction industry.
CARDIFF CASTLE TIMELINE
There have been settlements on the modern-day castle site for nearly 2,000 years, dating from the first Roman settlements in the first century AD
After the Norman Conquest, the Castle's keep was built and a number of Medieval fortifications followed
From 1866 the 3rd Marques of Bute employed architect William Burges to transform the castle
Within gothic towers he created lavish interiors which included murals, stained glass, marble and elaborate wood carving
The castle is undergoing a five-year, £8m renovation thought to be Britain's biggest current arts conservation scheme.
Workers on the site are working with materials ranging from Roman masonry to twentieth century reinforced concrete, requiring a wide range of skills.
David Cormican, president of BACH, said that colleges had high numbers of construction students, but too few were taught the skills needed to work on projects like Cardiff Castle.
"Visiting Cardiff Castle shows that traditional skills are still very much part of construction work," he said.
"Fifty percent of all construction work is maintenance and refurbishment.
John Edwards gives construction educators a tour of the work
"The castle refurbishment is a wonderful example of craftsmanship with a mix of the traditional and the high-tech. Just being taught how to do the minimum is not sufficient."
Gerry Reed, of BACH's Welsh national executive, added: "There are plenty of people learning construction, but they are just being taught the basics rather than to a level of excellence.
"People learning the minimum is a problem in Wales and UK-wide.
"Projects like the castle are important in that school pupils will see them and hopefully want to join the industry."
The Cardiff Council-run conservation project is expected to end in 2008.
Part of the work will allow the public access to the hidden tunnels in the Roman mural galleries for the first time since they were used as air raid shelters in World War Two.
The castle's wine cellars will be open to the public for the first time
The castle's north gate, which was built in the Victorian era on the foundations of the old Roman fort, is also being made accessible to the public for the first time.
From the gate, 2,000 years of Cardiff history will be visible.
The Castle Conservation Project Manager, John Edwards, said: "What will really add to visitors' experiences is the opportunity the visit the north gate and being able to get one spectacular view of 2,000 years of history.
"From there you can see the Roman ruins on which the walls are built, the Norman keep, the Victorian clock tower and the Millennium Stadium beyond.
"What we are most proud of in the restoration is that we will be giving the public access to areas they have never been to before."
When the renovation is completed, the castle's wine cellar will also be opened to the public for the first time, complete with the presses and vats which were last used to make Cardiff Castle wine in 1914.
The £8m conservation project has been supported by a £5.7m Lottery heritage grant - the largest ever awarded in Wales.