Yamunotri is the source of river Yamuna. This is considered as the seat of Goddess Yamuna by the Hindus.
Yamunotri is at a height of 3,293 metres (10,804 ft) in the Garhwal Himalayas, near Uttarkashi. Yamunotri is one of the four sites in the Chhota Char Dham pilgrimage.
History and legends, Geography, information about the Yamuna River and Yamunotri Temple are available in this wikipedia entry.
Web : http://en.wikipedia.org/wiki/Yamunotri