Walk into Las Médulas on a clear autumn morning and you meet a strange kind of silence. The red crags stand around you like the ruins of a cathedral built from clay, and the chestnut trees, some of them centuries old, drop their husks onto the path. It is a landscape made by an empire and then forgotten by it, left to grow over for nearly two thousand years.
The mine was worked by the Romans after their conquest of the north-west, and the gold went straight to the imperial treasury in Rome. Today you can enter one of the old galleries, the Cuevona, a tunnel the miners dug to let water rush through and bring down the hill, and walk through the dark where their lamps once flickered. The terrain above is easy to read from viewpoints like the Mirador de Orellán, from which the whole crater spreads below, red against dark green. UNESCO listed the site in 1997.
Getting here by bike is a pleasure. The final approach on the narrow road through Carucedo winds past a lake and through the chestnut woods, with just enough bends to be fun and little enough traffic to enjoy them. Go early on a weekday, before the coaches, and you may have the road to yourself. Take care with wet leaves in November and with the odd tractor that has right of way on this road by custom.
Carucedo and its neighbours are tiny, so bring a full tank. Cacabelos and Ponferrada, in the Bierzo, are the towns for fuel and a proper meal, with the Templar castle of Ponferrada well worth a visit. The valley produces Mencía red wine, peppers, pears and chestnuts, and the region's botillo, a stuffed pork dish, is a heavy winter treat. Chestnuts roasted at the roadside are a good excuse to stop in October and November.