Pasupatinath and Bodhnath
At the Hindu holy site of Pasupatinath (below) crowds of pilgrims gather to bathe and worship in the many shrines beside the sacred Bagmati River (a tributary of the Ganges). Located close to Kathmandu's airport, this is one of the most important Shiva temples in the whole of the subcontinent. Non-Hindus are not allowed in the main temple itself, but it is still fascinating to witness the hustle and bustle along the river banks, including the many cremations that take place on the ghats. There are also many other temples in the town which are of interest.
You will also spend some time at nearby Bodhnath, home to one of the world's largest stupas. The area around this impressive stupa is home to a large population of Tibetan exiles, and the shops sell Tibetan scrolls and even yak butter!