The definition of "Hallow" is something that has been "made holy, sanctified, consecrated". What consecrated place in the Harry Potter stories could this refer to?
...I have stolen the real Horcrux and intend to destroy it as soon as I can. I face death in the hope that when 你 meet your match, 你 will be mortal once more. R.A.B. (HBP pg. 609/569)
J.K. Rowling, via the "Rubbish Bin" sectino of her website gives the latest update on the status of the eagerly anticipated 7th volume of the Harry Potter Saga.