Stolen (or adapted) from Actraiser:
Pyramid full of the reincarnated human slaves who built it (now monsters and undead)
Bloodpool (a literal lake of blood inhabited by a sea monster)
- A source for the bloodpool could be a massive giant inside of a mountain (he is as large as the inside of the mountain) and a wound in the earth has caused him to bleed a literal river.
A fortress carved into the ice of a frozen lake (almost the entire thickness of the lake is frozen, with small pockets of icy water in the fortress and a small lake below; most likely something would allow the PCs to thaw out the lake and destroy the fortress)