The valley was once a great lake. Long ago, the water drained out through a gap in the hills, leaving behind a rich, flat plain perfect for farming. People built villages, then towns, then three small kingdoms - and a few hundred years ago each kingdom built its own beautiful palace square.
These palace squares are called Durbar Squares. They have carved wooden windows, brick towers, stone lions, and tall temples with layered roofs that look like umbrellas stacked on top of each other. Children still play football in them today, around statues that are hundreds of years old.
The valley is also famous for its craftspeople. Families pass down the skill of metalwork, woodcarving, pottery and weaving from grandparent to grandchild. The little brass bells you hear ringing on temples in the valley are made by the same families who have made them for centuries.
Walk through the old streets early in the morning and you will hear bells, smell incense and freshly baked bread, see cows ambling through a square, and meet shopkeepers opening up their wooden-shuttered shops. The valley packs an enormous amount of life into a small space.