Winter is coming!!! According to Gizmodo:
"Watchers on the Wall reports sets being constructed for Winterfell in Ireland have seen filming featuring Daenerys’ Unsullied arriving in the North—now armed with spears tipped with Dragonglass, after Jon got permission to mine Dragonstone’s reserves of the White-Walker-killing material.
Although battle scenes have yet to be filmed for a siege of Winterfell by the oncoming Walker horde, the site further speculates that it’s inevitable, given that exterior sets for the castle are being built instead of being saved for CG, indicating scenes set immediately around Winterfell are being planned"