Three towers of pale rock stand alone out of alpine meadow in the Italian Dolomites, and the path that loops around all of the Tre Cime di Lavaredo takes about four hours. The easy side comes first: ten kilometres of wide track, and in July flowers coming out of the rock crevices beside you. Then the path turns the corner and the mountain changes. The north faces are overhanging walls hundreds of metres high. Cima Grande's is on the short list of the six great north faces of the Alps, with the Eiger and the Matterhorn. Where the trail runs closest you can walk to the foot of them, and the climbers on the rock above are dots. The stone is dolomite, a coral reef that grew in a warm sea 250 million years ago, lifted thousands of metres and cut into towers. Only from the terrace of the Locatelli hut do all three line up shoulder to shoulder; the rest of the loop sees them edge-on.
People sleep at the huts for the first few minutes of light, when the pale north walls flush from grey to deep amber while the valleys underneath stay dark. The ground at the foot of the towers has its own history. From 1915 to 1917 the front between Italy and Austria ran through these mountains, and soldiers holding a line above 2,000 metres blasted trenches, gun positions and tunnels straight into the cliffs. The galleries through Monte Paterno, across from the towers, are still open. You walk them with a torch, and the peaks appear in the gun slots exactly as the men holding that line saw them. In 1933 Emilio Comici and the Dimai brothers spent three days forcing a route straight up the Cima Grande overhang, on the principle that a climb should follow the line a falling drop of water would take. That line is still up there, a few hundred metres above the path you walked in on.