The remains of what is thought to be the oldest settled agricultural community in Africa have been discovered on the outskirts of the Eritrean capital, Asmara.
Experts say the sites are of "global importance", and believe they could change the way the history of the Horn of Africa is viewed.
The sites are scattered across a large area of what is considered prime development land to the south and west of the city, much of it already earmarked for new housing.
Archaeologists from the University of Asmara are hoping to complete an urgent survey of the area, funded by the World Bank's Cultural Artifacts Rehabilitation Project (CARP), to assess the extent of the find before any building work commences. The project also plans to build an open-air museum on one of the sites, to provide information to the public and display items found there.
Using evidence collected during preliminary excavations, archaeologists have already pieced together a fascinating picture of life nearly 3,000 years ago. The settlement's inhabitants lived in stone houses, ate cows and goats, drank beer and farmed surrounding fertile land. They dressed in animal skins - tools for tanning and softening hides have been discovered, along with needles, stone implements for punching leather, and bronze buttons.
To conserve heat on the cool highland plateau, houses were entered through openings in the roof. For the same reason, according to archaeologists, homes appear to have shared walls. Hundreds of tiny bulls' heads, carved from stone, and thought to have ritual significance, were found around the sites. Gold earrings, bracelets and rings, copper and bronze daggers, and multiple-necked pottery jugs were also found in one excavation, which was possibly a burial chamber.
Experts believe the sites provide crucial new evidence that people lived in populated, settled farming communities in the Horn of Africa as early as 800 BC. "This is one of the richest heritage areas in Africa. It can be compared to Athens and Rome as it has excellent parallels to those places. There is a remarkable opportunity to use this as a centrepiece of national preservation," Prof Peter Schmidt, a specialist in African archaeology and dean of the College of Arts and Social Sciences at the University of Asmara, said.
The potential for tourism revenue from such important prehistoric sites is considerable. Last year, tourism in neighbouring Ethiopia generated more than US $77 million. Many tourists visited that country's ancient monuments at Aksum.
It is likely that the sites on the outskirts Asmara, which contain remnants likely to predate the Aksumite period (of the first to the sixth centuries AD) by many centuries, could also attract foreign and domestic tourists.
The Eritrean government, which is supporting the project, is anxious that the local community, including schoolchildren and university students, also has access to the ruins and use them to learn more about the country's history.
Arlene Fleming, a cultural resource specialist with the World Bank, said it was essential that local people were adequately informed about their cultural heritage so that they could make their own decisions about how to manage it. "Community participation is not a luxury, it is an absolute necessity if the community is to benefit economically. People should be able to help plan what kind of tourism they want and how to participate in tourism.
"This is a very exciting find," she said. "We hope these early projects will provide evidence that cultural assets are very significant and should be preserved and enhanced for the economic growth of the country. They are a factor for stimulating self-confidence and national identity and earning income," said Fleming.
Fleming said CARP was working to help the government find a balance between the need for urban development around Asmara and its desire to preserve the country's heritage. "It would be absurd to propose saving 1,000 [of the ancient] houses, but more realistic to document details of the site and to save a few houses so that people can see and learn from them. What archaeologists want is adequate time to do research."
Naigzy Gebremedhin, the coordinator of CARP, said a consultation process was under way to ensure that the people of Asmara, and in particular those living close to the sites, were properly informed about them.
"We are aware at CARP that it is an endangered area and that it is in the path of urban development, but there has to be a compromise between the preservation of heritage and the provision of basic infrastructure. Asmara needs to grow to meet the basic needs of people, so it is going to extremely challenging," he said.
But archaeologists fear that it may be too late to save some of the sites. They are seeking funding to erect a fence around one excavation, which has been partly destroyed by bulldozers digging stone for road building. Another potentially important site has already been subdivided for new housing.