Jova town from SQ. The woods from Castlevania 3. The Dungeon from Castlevania 4. Death Tower from Castlevania Adventure. The Villa from 64 and LoD. "Underground Waterway" from Circle of the Moon. "Dark Palace of Waterfalls" from Lament of Innocence. "Training Hall" from Order of Ecclesia. And, of course - "Nest of Evil" from Portrait of Ruin. Crazy place...
There are too many beautiful stages in Castlevania! I can't choose one.