Winterfell is the capital of the the North, one of the Seven Kingdoms Of Westeros and the seat and the ancestral home of the House Stark. It is a very large castle located at the center of the North, from where the head of House Stark rules over his or her people. A small godswood is enclosed within the walls. The castle is located alongside the Kingsroad as it makes its way from the Wall to the capital of the Seven Kingdoms, King's Landing, more than a thousand miles to the south. It is situated atop hot springs which keep the castle warm even in the worst winters. Winding tombs below the castle contain the remains of Stark kings and lords and record the history of the ancient family. According to Maester Luwin, there are hidden passageways built in the castle so its Lords could escape. The castle has stood for millennia.
During the War of the Five Kings, Winterfell is taken by Theon Greyjoy from Bran Stark, but the castle is put to the torch by Ramsay Snow after Theon is betrayed by his own crew. This burned out the wood portions of the castle, though the core stone structures remained fundamentally intact, as did the enclosed godswood. After the surrenderof Moat Cailin, the Bolton army relocated to the ruined castle in order to restore it as the seat of the rulers of the North.
Winterfell remained in the hands of Roose Bolton, who betrayed Robb Stark at the Red Wedding, for a time. It was first contested by Stannis Baratheon at the Battle of Winterfell, but the sickly, tired Baratheon army was defeated. After murdering his father, Ramsay Bolton held onto Winterfell until his defeat at the Battle of the Bastards, at which point the castle was returned to House Stark's ownership, with Sansa Stark being named the Lady of Winterfell.