Amazon Italy has posted official pictures of 4 brand new Harry Potter sets. The Hogwarts Clock Tower set connects to the main Hogwarts Great Hall (75954) like the Whomping Willow (75953) set, if you have it.
EDIT: Photos are now clickable to see a larger version. Sorry about that.
75945 Expecto Patronum (121 pieces)
75946 Hungarian Horntail Triwizard Challenge (265 pieces)
75947 Hagrid Hut Buckbeak’s Rescue (496 pieces)
75948 Hogwarts Clock Tower (922 pieces)