On a hilltop overlooking the western outskirts, Swayambhunath (colloquially known as ‘the Monkey Temple’ for its resident population of macaques) has been sacred since the beginning of written history – and probably well before. A magnificent stupa, with gilded tower and pair of huge, all-seeing eyes, forms its iconic centrepiece. Early morning or late evening, when smoke from incense offerings and dozens of yak butter lamps fill the air, are the best times to visit.