In the Monster Prison you will find the Champion.
After defeating this monster there will be a small door you can pass through. Here you will enter a small coridor with 2 items in it.
On the ground there is a stepping stone, (the stone is a mechanism that opens a metal door) just walk over it; downstairs and to the right.
There you will find a chamber with a human skull and a chest. (notice: when you enter the chamber the metal door will come falling down, and closing the exit, but this is easily solved with the handle next to the chest.)
When leaving the rome you can go two different ways.
To the left (also the way back up to the monster prison) is also another chamber with items.
To the right you have to smash some barrels to get through, this will take you behind the bars in the dead end in the Royal Chamber. There are two small spiders there and a little item.
For the moment that's it.