For the last thirty years the conservation movement, assisted increasingly by entrepreneurs and property companies, has set out to revive ailing historic buildings through imaginative reuse - warehouses have been converted into loft apartments, barns into homes, corn exchanges into shopping malls, power stations into galleries and cotton mills into business centres. Some of the great industrial sites now coming vacant, whether nineteenth century collieries or twentieth century power stations, and more recent defence installations are simply too monumental to adapt and indeed may consist of structures rather than buildings. We need urgently to identify which structures ought to be saved and develop a coherent strategy and philosophy for their conservation. The British tradition has long been to turn all such installations into scrap, but some of these places are awe inspiring landmarks of great historical importance.

Germany's Ruhr has pioneered a different approach, reviving these places as open air monuments where nature is allowed to take over and a new beauty softens the stark remains of concrete and steel. Thousands of trees are planted and wild flowers grow through the disused railway lines and over walls. The public is encouraged to explore by day while flood lighting of the main features at night allows visitors to remain long into the evening. Restoration is not attempted. Instead structures are subject to basic maintenance and left to stand exactly as they are. Routes are opened up, sometimes with new walkways taking people up 50-60ft above the landscape as they climb up to view blast furnaces and colliery winding gear. This is the approach that could be explored for blastfunaces, the cooling towers of post war power stations and the amazing pipescapes of oil refineries.