White Harbor

White Harbor is a city in the North. It is one of the major cities of Westeros, located where the White Knife River flows into the Bite. It is the seat of House Manderly, a vassal house holding fealty to House Stark of Winterfell. White Harbor is the main seaport of the North and is one of only five settlements in Westeros large enough to be called a city, though it is the smallest of the five (King's Landing, Oldtown, Lannisport and Gulltown).

Season 1
Ros tells Theon Greyjoy she is taking a ship from White Harbor to get her to King's Landing as fast as possible.

In the books
In the A Song of Ice and Fire novels, White Harbor is the main center of trade and merchant activity in the North. Though the smallest of the major cities of Westeros, it is still far larger than any other settlement north of Gulltown and Braavos.

The city's harbour is defended by an outer sea wall almost a mile long, with tall towers located every 100 feet along the wall. The mouth of the White Knife River is guarded by the Seal Rock, named for the animals that dot its flanks. The city itself contains an old, mostly-abandoned godswood, with most religious worship taking place at the Snow Sept. The oldest building in the city is the old keep, the Wolf's Den, which now serves as the city prison. The city is built around the flanks of a hill, with the Manderly keep, New Castle, located the summit of the hill, which commands a wide view of the harbor and surrounding land.

The city was founded at the order of King Jon Stark several millennia ago to provide a trading link with the rest of Westeros. The Manderlys, exiled from the Kingdom of the Reach, were given control of White Harbor a thousand years ago.

In the novels, Catelyn Stark and Ser Rodrik Cassel use a ship from White Harbor to get to King's Landing around the same time that Eddard Stark and his party, travelling overland, arrive. However, in the television series there is no indication they used this method of travel.