So, we aren't lucky enough to have a rich, eccentric, childless uncle. But if we did, we bet he'd hang out in a room like the one Poe describes in this poem. We bet the curtains would be "silken" and "purple" (line 13). We bet the cushions on the chairs would have velvet violet lining" (line 77). The room in this poem feels like the perfect place to brood and mutter to yourself, especially if you don't have to work and can spend all your time thinking gloomy thoughts.
Poe doesn't say what exactly this room is, but we imagine it being a library, shelves piled high with musty old books. There's probably a pipe and a bottle of brandy on the side table. We can see the spooky light from the lanterns playing over the scene, making everything seem even stranger and more exciting.