On the side of Baseline Road in Narahenpita there’s a wall mural depicting hell/the underworld and all the terrible torments that await (beheadings, eye pokings, punching in the stomach). If you’re stopped in traffic it’s kinda amazing.
If you want to walk through depictions of hell Gangaramaya Temple has a good set of painting upstairs. Otherwise, the Hell Wall in Narahenpita is a good (and well painted) set of images to ponder while you’re thinking terrible thoughts in traffic.