From the area close to the 3 Buddhas, stretched TIbetan prayer flags. These were very common in Kathmandu and, I am told, are frequently seen throughout the Himalayas. They are imprinted with ancient Buddhist prayers, mantras and powerful symbols and are said to produce a spiritual vibration that is activated and carried by the wind across the countryside. Each color corresponds to a unique primary element; earth (yellow), water (green), fire (red), air (white), and space (blue).
Wikipedia has a detailed explanation: Wikipedia Prayer Flags