What is the setting of The Sirens of Titan by Kurt Vonnegut?

The setting for Sirens of Titan ranges across the solar system and beyond, into the wispy regions of time and space. Much of the action takes place on Earth, in the United States, with a large segment of the story occurring on the planet Mars. The imagined deep caves of Mercury provide the setting for a period of isolation of the main character, Malachi Constant, who from there returns to Earth and eventually travels on to Titan, a moon of Saturn.