Shali rises in the centre of Siwa like a crumbling sandcastle. Its walls are made of kershef, a local mix of salt-laden mud that turns rock-hard in dry weather and collapses in rain. The original fortress was a single dense knot of houses stacked vertically to save space within the walls, with narrow tunnels for streets.
You can walk up through the ruins to the top, where a restored lookout gives the best view of the oasis: palm groves stretching to the salt lakes, the desert beyond. Sunset is the time to come — the mud walls glow orange and the muezzin's call drifts up from the modern town below. The restored Tinda Mosque at the base of the hill is still in use.