South and east of St-Flour stretch the wild, rolling, sparsely populated wooded hills of the Margeride, one of the strongholds of the wartime Resistance groups. If you have your own transport, the D4 makes a slow but spectacular route east (92km) to Le Puy, crossing the forested heights of Mont Mouchet, at 1465m the highest point of the Margeride. A side turning, the D48 (signposted), takes you to the national Resistance monument by the woodman's hut that served as HQ to the local Resistance commander during the June 1944 battle to delay German reinforcements moving north to strengthen resistance to the D-day landings in Normandy. There's an eco-museum here (May to mid-Sept daily 9.30amnoon & 27pm; mid-Sept to mid-Oct MonFri 9.30amnoon & 27pm, Sat & Sun 10amnoon & 26pm; €4), sketching the progression of the Resistance movement in the area. The views back west from these heights to the Cantal are superb.
Further south, the modern autoroute crosses the gorge of the River Truyère beside the delicate steel tracery of the Viaduc de Garabit, built by Gustave Eiffel (of Tower fame) in 1884 to carry the newly constructed rail line; experience he put to important use in the Tower. Not far away, about 20km south of St-Flour and perched above the waters of the lake created by the damming of the Truyère for hydroelectric power, are the romantic ruins of the keep of the Château d'Alleuze, stronghold in the 1380s of one Bernard de Garlan, a notorious leader of lawless mercenaries employed by the English in the Hundred Years War to sow panic and destruction in French-held parts of the country.