Among the site's most remarkable buildings is a 15th-century cylindrical tomb.

Tourists flock to the area known as the Cradle of Civilisation in southeast Turkey, where there is rich evidence of settlements dating back 12,000 years.

Half the world away, the Brazilian Amazon has become a must-visit destination for adventure-seekers. In the south of the Amazon Basin, the Kayapo and other indigenous groups have depended on the Xingu River since time immemorial.

Although different in so many ways, these places are united by one unwanted factor: their very existence is under threat.

The world stands to lose some of its most important cultural and natural heritage as the foundations of two controversial large-scale dams are being laid.

More than 20 cultures have left their mark on the town over the millennia, including the Romans, Byzantines, Arabs and Ottomans. All will be lost under water

The Ilisu dam in southeast Turkey, and the Belo Monte dam in the Amazon, are going ahead despite widespread opposition and resistance both at home and from abroad.

In Turkey, the ancient town of Hasankeyf will be flooded out of existence. Hasankeyf and the surrounding Tigris Valley is the only area in the world that meets nine out of 10 criteria of Unesco World Heritage Sites. But the Turkish Government has refused to apply for World Heritage status – it has other plans.

Visitors to Hasankeyf today can still wonder at its rich biodiversity, 300 medieval monuments and thousands of man-made caves, where the first settlers lived in the Bronze Age, up to 12,000 years ago.

Built on the banks of the Tigris in the fertile crescent of Mesopotamia, Hasankeyf is thought to be one of the oldest continuously inhabited settlements in the world. Historians estimate at least a third of it has yet to be excavated.

More than 20 cultures have left their mark on the town over the millennia, including the Romans, Byzantines, Arabs and Ottomans. All will be lost under water, save for relatively few artifacts the Turkish Government has vowed to move before the flood.

Work on the Ilisu dam continues in defiance of court rulings halting the dam, and the withdrawal of funding from European credit agencies in 2009 when the Turkish Government failed to meet almost all the criteria to protect the environment, cultural heritage and local communities

In Brazil, Belo Monte’s two reservoirs and canals will flood a total area of 668 square kilometres, of which 400 square kilometres are standing forest. Up to 40,000 residents will be displaced, including 25,000 indigenous people. A permanent drought will be caused on the river’s Big Bend.

This is an area rich in biodiversity. Scientists fear that hundreds of dams, including the Belo Monte project planned in the Amazon Basin, may cause the extinction of 1,000 fish species, which amount to one-third of all fish species in the Amazon. This will be the last great wilderness no longer.

Dr Philip Fearnside of the National Amazon Research Institute says forests flooded by Belo Monte’s reservoirs would generate enormous quantities of methane, a greenhouse gas that is 25 times more potent than carbon dioxide (CO₂).

An international movement called Damocracy has attempted to unite the campaigns to stop these destructive projects and expose the myth of dams as clean energy. It recently released a short documentary by award-winning filmmaker Todd Southgate, which may be watched at: www.youtube.com/DamocracyTV.

Visit www.damocracy.org or www.amazonwatch.org for more information.