Damn you're really going all out on that! Good luck with that project!

As for the hallways, yeah they're most likely purely decorative. There may actually be a logical end to the hallways, perhaps a door that leads to some room some NPC would use for whatever reason, but we don't need to know for what (probably something kinky, I should think ;D those Ishgardian types man, never know what they're up to behind the scenes).