I know there is one in the Sutri garden, to get down to the bathing cove.

How priceless if we've happened to light upon it.

Is that door open?
I'm going to see." Peachy ran down the steps, turned the handle, and somewhat to her own astonishment found the door unlocked.

She was peering into a long dark tunnel, at the end of which could be distinguished a faint glint of light.

This was indeed an adventure.