Wadi Al-Hitan — Whale Valley

Wadi Al-Hitan lies in the Western Desert in Fayoum governorate, beyond the lakes of Wadi El-Rayan, about 150 kilometres south-west of Cairo. The last stretch is off-road.

It is a shallow desert basin of yellow sandstone and wind-carved rock, with a marked walking trail through it. Along the trail, lying where they were found, are the fossil skeletons of whales.

These are not just old bones. They are archaeocetes — Basilosaurus and Dorudon — from around forty million years ago, when this desert was the floor of the Tethys Sea. What makes them one of the most important fossil sites in the world is that they still have small hind limbs, with knees, ankles and toes, on animals that were already fully marine. The transition from a four-legged land mammal to a whale is documented here in a single valley, at a density found nowhere else.

It was inscribed by UNESCO in 2005 as Egypt's first natural World Heritage Site, and the presentation is unusually good for Egypt: the skeletons are left in place rather than removed, and the trail takes you past them in the open with almost nothing between you and the fossil.

The landscape alone would justify the drive. Wind-eroded sandstone hills, a floor scattered with fossil shells and shark teeth, complete silence, and the kind of emptiness that photographs badly and stays with you.

The fossils were first noted by a British expedition at the start of the twentieth century, and serious excavation followed through the decades after. Hundreds of skeletons have been recorded within the protected area.

Basilosaurus itself carries a mistake in its name: the first bones, found in America, were taken for a giant marine reptile — 'king lizard' — before anatomists recognised a whale. The Egyptian valley's own contribution came later and was larger: complete skeletons, hind limbs and all, plus stomach contents showing that Basilosaurus ate the smaller Dorudon whose skeletons share the valley.

The whole Fayoum depression is a major palaeontological region. Nearby beds have produced early primates, elephant ancestors and sea cows, and the sequence of rocks records the Eocene shoreline retreating north.

The site's museum — the Fossils and Climate Change Museum, opened in 2016 and set low into the landscape — lays the star specimen out full length: an eighteen-metre Basilosaurus, the largest intact skeleton found here.

• Whale skeletons lying in the sand along the marked trail
• Hind limbs on animals that had already returned to the sea
• The eighteen-metre Basilosaurus laid out in the museum
• Fossil mangrove roots, shark teeth and shells across the valley floor
• Wind-carved sandstone formations across the basin
• The on-site fossil and climate museum