ISTANBUL (AP) — UNESCO is adding Mali's Old Towns of Djenne, famous for their adobe architecture, to its list of World Heritage in Danger sites.

The decision was made Wednesday in Istanbul where the 40th session of the World Heritage Committee is being held.

The committee expressed concern over the historic towns, saying insecurity stood in the way of "safeguarding measures" and appealed to the international community to support Mali's efforts to protect the site.

Inhabited since 250 B.C., the Old Towns of Djenne became a market center and a major link in the trans-Saharan gold trade. They were also a center for Islamic learning in the 15th and 16th centuries. Some 2,000 traditional houses, raised on hillocks to avoid seasonal floods, have stood the passage of time.

UNESCO designated the area a World Heritage site in 1988.