Neverwhere by Neil Gaiman
For more subversive, literary fantasy, try these next…
Peter & Max by Bill Willingham for fairy tale deconstruction and shadowy charm
The Brides of Rollrock Island by Margo Lanagan for painfully gorgeous language and magic that crawls right up your spine
Magic Casement by Dave Duncan for a sneakily wonderful main character
Soon I Will Be Invincible by Austin Grossman for head-spinning writing and thinking, and inside-out archetypes
The awesome Rainbow Rowell guest edited GBY!