Riverrise was the highest point in the Edgeworld, and the source of the Edgewater River. It was a sacred place, and the origin of all life in the Edge. It was considered by most to be a myth, as its exact location had been lost after the Time of Enlightenment. However it was rediscovered during the Third Age of Flight, and a great city was built around it.
Due to the abundance of chine in the vicinity, the spring of Riverrise had magical healing qualities, and those who drank from it would remain eternally youthful. Once every few thousand years the spring would run dry, and the Mother Storm would return to renew it.
In the First Age of Flight
In the First Age, Riverrise's location had long been forgotten and the majority of the educated populace considered it a myth. Around the year 35 ᴇ.ʏ., the spring began to dry up. The Mother Storm prepared to return and renew it, but it in the intervening millennia since it had last appeared the city of Sanctaphrax had been built in the way. Unless Sanctaphrax was moved, the Storm would expend all its energy on destroying it, and would be unable to reach Riverrise. Disaster was averted when Twig severed the Anchor Chain, allowing Sanctaphrax to drift away and the Mother Storm to proceed unhindered.
In The Third Age of Flight
The City of Riverrise
Riverrise was rediscovered by Golderayce One-Eye during the Third Age of Flight, and by the time of Nate Quarter's adventures, had expanded into a great city. Known as the City of Night because of the eternally dark forest that surrounded it, it was famed for the healing properties of its waters, and the sick and dying flocked to it from all corners of the Edge.
However the city was not free from corrupution and injustice; Golderayce and his custodians ruled the city despotically, allowing ordinary citizens to access only the relatively weak water which ran down into the city from the spring. Even this was heavily regulated via a system of sluices. Those who dissented were murdered by the custodians' team of assassins.
Golderayce was finally killed by Nate, and the sluices were opened to allow the water to flow unrestricted. The Keep was demolished, allowing all citizens access to the spring of Riverrise.