During my childhood, my family lived in Gloucester, Virginia from 1968 to 1971. My sister and I both remember a book we had out from the Gloucester Library at the time, but we have no memory of the title. It was a children’s story with two children, I think a boy and girl, probably brother and sister, exploring a mysterious castle or tower. The book was hardbound in green (may have had gold illustration in the binding) and was a somewhat tall rectangular shape but not too thick. There were illustrations inside in black and white, I believe. Unfortunately, that’s all we can remember. Any help would be appreciated. Thank you!