Regulus’s bedroom was slightly smaller than Sirius’s, though it had the same sense of former grandeur.
Dumbledore had shown Harry that Voldemort sought grandeur or mystique in his hiding places; this dismal gray corner of London was as far removed as you could imagine from Hogwarts of the Ministry or a building like Gringotts, the Wizarding banks, with its gilded doors and marble floors.
There are no more uses of "grandeur" in the book.
Show samples from other sources
The hotel is well past the days of its grandeur.
What have wealth or grandeur to do with happiness?