Well done! You've found one end of the secret tunnel into the castle.

Do you know where the other end is?

There's a secret passage into Nottingham Castle. It's called Mortimer's Hole because on October 19th 1330 supporters of Edward III crept through a tunnel into the castle and captured Roger Mortimer, Earl of March. Mortimer and the young king's mother Queen Isabella had been ruling the country and their capture enabled Edward to gain control. It is not certain, however, if this is the actual tunnel used by the conspirators.