A few posters I bought from the campus poster sale at the start of the year. (Specifically, a woodblock print, a solar system map and a Cowboy Bebop poster.)
I have a huge window with a nice view (in a university owned apartment no less!) so I can afford to skimp on the other walls.
I mean… you’re surrounded by trillions of perfect nanotech devices. They’re called MOSFETs, and they make literally the entire modern world go round.