British artist Francis Bacon (1909—92) was a giant of 20th-century art and an individualist. His surreal, figurative imagery has many fans and a few followers (such as Lucian Freud), but it’s mostly inimitable, adding up to a uniquely dreamlike—and sometimes nightmarish—body of work. Last summer the Tate Liverpool put together an exhibit, “Francis Bacon: Invisible Rooms,” which focused on an under-explored motif in Bacon’s portraits: his subjects are often surrounded by an almost-invisible cubic or elliptical cage, a “ghostlike frame” that establishes an isolated room or space in which their emotions can be visually unleashed. PROVOKR offers a mesmerizing tour of the show above and below.