Garabit: Eiffel's Viaduct over the Truyère and the Castle of Alleuze

Required Activities

• From the viewpoints on both sides of the gorge, count the seven puddled-iron piers — the two tallest are 80 m — and pick out the three central bays that make up the 165 m arch, 52 m high, over the deepest part of the valley. The whole thing is held together by 678,768 rivets, and the paint is a specific colour: rouge Gauguin, put on between 1992 and 1998

• Take the boat out from Garabit onto the lake and look up at the viaduct from the water — from down there the deck is 95 m above you, where before the dam of 1959 it stood 122 m above the Truyère, so about twenty-seven metres of the old gorge is under the keel

• Walk up to the ruins of Alleuze on its promontory: a square castle with round towers at the corners, 12th century in origin, held in the 1380s by the Gascon routier Bernard de Garlan with as few as three men until the king's man bought him out in 1390, burned by the townsmen of Saint-Flour in 1405 so no one could do it again, and then rebuilt by those same townsmen in 1411 on the same plan because the owner made them. Find the chapel of Saint-Illide beside it, rebuilt in the 15th century

• Find the plaque on the masonry access trestle at the end of the viaduct — 'A Léon Boyer, de Florac, les cantaliens reconnaissants', put up for the centenary in August 1984 for the engineer who designed the crossing and died in Panama in 1886, two years before the first train ran. Then wait for a train: they still cross, at a walking-pace 40 km/h to spare the ironwork