The building itself rises only a few metres above the ground but the granite roof being laid by the operatives of Stone Central (NW) Ltd is well over 1,000m above sea level. The reason is that the roof they have been laying is on the new visitor centre at the top of Snowdon - and to the irritation of some of the locals it is Roriz granite from Portugal supplied by Hardscape in Bolton that is being laid rather than the local granite.

The walls of the centre do use local material - the igneous overburden of Alfred McAlpine Slate\'s now moth-balled Cwt-y-Bugail slate quarry. But for the roof it was the Portuguese stone that was considered to provide the best solution and, according to Ian Mercer of Stone Central, there are 3,800 blocks of it on the roof, including a hefty bullnose edging (see picture below).

It was all transported to the summit by the rack and pinion railway that also had to take the operatives the hour\'s journey to the summit and back down again each day. Some of the building materials were taken up by helicopter, but the crates of stone were bulky. In any case, the helicopter only flew when the wind was not too strong, whereas the train managed to make the journey most days in spite of the heavy rains this summer.

The roof is built up using a Kalzip cladding system with a Halfen frame on to which the granite is fixed. Open joints allow the rain through to gutters underneath.

The building has been made watertight but work has to stop in the winter because the extreme weather can form sheets of \'rime ice\' that can bend scaffolding. Work will resume in the spring and the visitor centre should be open to the public in time for next summer\'s holiday season.