The Belvedere is a small flagstoned terrace at the southern tip of the village, where Via Fieschi runs out and the land drops 100 metres straight to the sea. It is the single best viewpoint in Corniglia, and arguably the best in the Cinque Terre — you can see Manarola and the headland beyond Riomaggiore to the south, the long curve of cliff and vineyard stretching back toward Vernazza in the other direction, and nothing but the Mediterranean in front.
Come at sunset if you can. The terrace gets busy in summer but stays small enough that the crowd is part of the atmosphere rather than a problem. There are benches along the wall and usually a guitar or two by dusk.