Gouveia is where the Serra da Estrela stops being a map feature and turns into somewhere people live. It is an old granite town on the western flank of the mountains, with solid stone houses, a mid-sized main square and a long history of sheep, wool and cheese. At the end of a day crossing Portugal's highest mainland range, it makes a good place to get off the bike, because the climate here is gentler than up on the plateau and the evenings are mild.
The mountains behind it are the interesting part. The Serra da Estrela is the highest range in mainland Portugal, with the summit at the Torre close to two thousand metres, and its character is almost un-Iberian: round granite domes, boulder fields, small lakes, heather and broom, and valleys scraped into a clean U shape by glaciers during the ice ages. The Zêzere river runs in one of those valleys on the eastern side, near Manteigas, and the contrast with the dry plains beyond is striking. Snow lies here in winter, and in late autumn and spring fog can drop on the upper road with almost no warning, so look at the sky before committing.
Ride-wise, you arrive from the high road in a long descent of smooth bends, with wide views and not much traffic outside holiday weekends. The surface is generally good and the curves are open, so you can ride it with a bit of rhythm, though livestock and the occasional dog on the road deserve respect. Late spring, when the broom flowers yellow across the slopes, and early autumn are the best times; August is hot below and busy above.
The great local product is Serra da Estrela cheese, made from sheep's milk and curdled with thistle flower, soft enough to eat with a spoon when it is properly ripe. Ask for it with bread and a bit of local wine. The sheepdog of the region, the cão da Serra da Estrela, is a big, calm, slightly serious animal, and you may meet one. Fuel is simplest in Seia, about thirteen kilometres away, which is a bigger town with several stations and plenty of cafes, and Gouveia itself has the usual small-town options.