A definite tourist requirement while in Kathmandu is a visit Durbar Square, the plaza in front of the old royal palace of the Kathmandu Kingdom. Grab a map, pay your entrance fee and explore all the lovely temples and palaces. The architecture is unique from temple to temple, so take your time and visit them all. This is a very popular tourist spot, so I would recommend going in the early morning or late evening to avoid some of the crowds.