Gangtori temple:

Hindu mythology says that the temple has been built where the Ganges originally began. Gangotri is also one of the Char-Dham 4 Holy places amongst Hindu pilgrimage sites

Pandav Gufa (Cave):

The cave where five brothers of Mahabharata stayed during their exile.. The cave is about an hour's walk from the Gangotri temple is a home for a sadhusaints who meditates and lives there. Remember to take off your shoes when entering the cave.