Behind my DM seat are shelves full of rulebooks and adventure modules; difficult to photograph as there's too much stuff in the way. Behind me where I'm sitting is a shelf full of boxed sets and non-D&D RPG bits. All over the gaming area there's shelves covered with character pieces, monster minis, and assorted gaming props; and there's also shelves, boxes, and filing cabinets containing various player-side material (mostly character sheets) and archival bits from my old campaigns.
Amazing what one slowly accumulates in 35+ years of doing this...
Extra points for being so tidy. My shelves are shambolic messes. The 5e stuff is decently organized, but everything else could really do with some proper organization.
These photos are both incomplete and outdated (I sold all my 3.x books last weekend), and to the left I have a bunch of 5e and Tails of Equestria stuff