You can easily spend a week in Kathmandu Valley without getting bored. The valley surrounding the capital of Nepal is full of cultural and historical sites, most Unesco heritage, and are all worthwhile checking out. Every street reveals yet another interesting collection of hand painted shops, exotic spices, colorful fabrics and many, many shrines. The people in Nepal live among their gods, always sacrificing and praying whenever they can. Three cities in the valley are the most important, Kathmandu off course, Patan and Bhaktapur. Each has their own Durbar Square filled with ancient buildings and temples. Bhaktapur, for us, was the most memorable and beautiful, mainly because they don’t allow traffic on the square, while on the others, you are always in danger to be run over. If you can, spend a couple of days in Bhaktapur.
Swayambhunath and the stupa in Boudhanath are two important and very impressive Buddhist sites, you feel a lively Tibetan vibe in Boudhanath with many pilgrims coming to this place.
What Varanasi is to India, the holy Bagmati river is to Nepal. It’s the most important Hindu site where Shiva is worshiped in form of destruction (death and cremation) and creation (lord of every animal). It’s an intense experience watching people grieve during the purification and cremation process. Hire a guide so you can better understand what is going on and you know what you can and can’t do in this place.