Harry Potter 'Hogwarts Castle' Blank Card, Envelope & USPS Harry Potter Stamp Harry Potter Hogwarts castle illustration blank greeting card. Lovely illustration of the Hogwarts School of Witchcraft and Wizardry castle on front cover. Single 5" x 7" card and white envelope plus USPS Harry Potter postage stamp. Great for birthday, graduation, thank you, missing you, get-well-soon, and many other messages. Will include one USPS Harry Potter first class one ounce forever stamp when purchased from Hogsmeade Station Gift Shop.