The Maker of Universes (World of Tiers, #1)

When Robert Wolff found a strange horn in an empty house, he held the key to a different universe. To blow that horn would open up a door through space-time and permit entry to a cosmos whose dimensions and laws were not those our starry galaxy knows.

For that other universe was a place of tiers, world upon world piled upon each other like the landings of a sky-piercing mountain. The one to blow that horn would ascend those steps, from creation to creation, until he would come face to face with the being whose brain-child it was. ... more>>