Prayag's

Devaprayag:
This is the place where the Alaknanda and Bagirthi rivers mingle to one another and the river falls down as "Aadhi Ganga", In Devaprayag, Brahma devar, King Dasarathan and Sri Ramar are believed to have done tapas. And an Mutt is installed by Aadhi Sankarar here.
Rudraprayag:
Rudraprayag is the place where river Mandakini joins the Alankananda river. Here a temple for Rudran is found Mandakini river rises from Kedarnath and it joins Ganga and then towards Madhya Maheshwar near Gupta Kasi. In Gupta Kasi a famous temple for Ardha Nareeshwarar is found (Artha Nareeshwarar is one of seva given by Lord Shivan where he is found as one part of his body and another side for Uma devi).
Karnaprayag:
Karnaprayag is the place where Karnan did strong tapas to get all sorts of mantra arrows.
Nandaprayag:
Nandaprayag is the place where the Nandakini river arises and joins Alaknanda. It is said that king Nanda did a severe tapas here in this place.

Vishnuprayag:
It is believed that this is the place where Pandu King did strong tapas towards the Emperumaan Sri Vishnu and it is said that the Pandja Pandavas born here.