Entire cities built of mud.

• Position: UNESCO/UNDP Cultural Heritage and Development Project - World Decade for Cultural Development, 1988-1997

This inscription was found at the base of a raw earth pyramid near Cairo: "Do not disdain me when comparing me to pyramids of stone: I am as high above them as Jupiter is above the other gods, for I was built in bricks made from the silt at the bottom of the lake".

For more than 10,000 years, earth has been used to build houses, palaces, aqueducts, temples and entire cities from those of Mesopotamia to the Aztec empire, in summer and warm in winter.

Some 500 million families in the third world will need shelter before the end of the century. But traditional adobe technology, which could help solve the problem, is in danger of disappearing.

"People insist on waiting to obtain a tin roof over 'European earth' that is cement", says Tanzanian President Julius Nyerere. "If we are to progress ... we must overcome these mental blocks. The majority of the people do not have means to buy a cement house. Therefore, if we do not help them build a house made of improved traditional materials, we will have done nothing to help them live in a decent home."

Improving adobe technology so it can be used in the modern world is

"We moved from an elitist concept of conservation of temples and works of art to the relationship between cultural heritage and development", says Sylvio Mutal, of Peru, who heads the Project. What was strictly a cultural heritage effort has become, according to him, "a development project of a multidisciplinary nature with culture as the axis".

Now he and his colleagues are involved not only in the rehabilitation of historical centres but also in cultural industries, social archaeology, and...