The grandfather of my friend Bob has built a perfect square castle for himself and his family and divided it into 9 perfect square halls and made an armoury in the middle one.
Bob's father divided each of the remaining 8 halls into another 9 perfect square halls and in each middle one he made a garden.
Bob himself divided each of the remaining 64 halls into 9 perfect square halls and in each middle one he made a swimming pool and the rest became bedrooms.
Recently Bob told me that he managed to walk through each bedroom visiting each one of them exactly once and returning back to the one where he started. Each bedroom has a door to another bedroom if they share a wall.
And I being myself decided to check if it's possible before fully trusting him, but I do not have a lot of time, so I'm asking you: can I trust Bob or does he just want to look cool?