After a good start, Curse of the Crimson Altar loses a bit of momentum before getting back on track, but anyway, the cast is the true star here: Boris Karloff (this is one of his last movies), Barbara Steel and Christopher Lee united. For that reason alone and some nice cinematography the connoisseur of classic horror should have watched this at least once in this existence before entering the next domain and greeting the Great Old Ones. My rate 5 + 1 for starpower. Recommended for the aficionado of horror with some inclination to nostalgia.