In the Inverted Castle, the player must unite 5 relics of Dracula in order to unlock the path to Dracula (Those being a Ring, Heart, Rib, Tooth and Eye of Vlad), a concept first utilized in Castlevania 2. All five are guarded by bosses based on the original Castlevania bosses.

In addition, every boss in the Inverted Castle save one are previous bosses and even playable characters in the series. Aside from the aforementioned five, the player meets Galamoth (Kid Dracula), Shaft (Rondo of Blood), the Doppleganger (Castlevania 3), three falsified heroes from Castlevania 3, with whom Alucard himself was a companion, and of course Dracula. The one exception is Beelzebub, whose first appearance was Symphony of the Night.