Climb the Renard slag heap near Denain and you are standing on two centuries of work. Terrils are the waste rock hauled out of a mine in wagons and tipped, one load after another, until the pile became a hill. This one, the Fox, lies barely a kilometre and a half from the middle of Denain, a town of twenty-one thousand people that grew fat on coal and steel. It is named after the Renard pit, and it was down the Renard pit in 1884 that Émile Zola was lowered while he researched Germinal, notebook in hand, listening to the men who worked the seam.
The coalfield ran in a long arc from here through Valenciennes and Douai to Lens and Béthune, and the whole landscape was shaped by it. Since 2012 the basin has been a World Heritage landscape, and the terrils are a large part of the reason, because nothing else says so plainly what the industry did to the land. From the top you can pick out other black cones on the plain, and the wind turbines beyond. Nature has quietly taken the heap over: birch, buddleia and thin-soil wildflowers, and birds that like warm, dry slopes. Paths wind up the flanks and it is an easy half-hour walk, dusty in summer and slick after rain.
The roads below are flat and gridded, joined by small roundabouts and lined with brick houses. Subsidence has left some surfaces rippled, and cobbles, the pavé, turn up where you least expect them. The famous cobbled roads of Paris-Roubaix lie not far to the north-west, and wet pavé will happily send a bike sideways, so give it respect.
Denain has fuel, supermarkets and bakeries; Lourches and Escaudain are small and close. Workaday cafes serve strong coffee, and a paper cone of frites is never far away. Pick a dry spring or autumn day, wear shoes you do not mind getting grey, and go up for the view.