Storm's End

Storm's End is the ancestral seat of House Baratheon, and one of three major castles currently held by the royal house, the others being the Red Keep in King's Landing and the island fastness of Dragonstone. Stannis Baratheon is the current Lord of Storm's End. Storm's End is a formidable fortress, located on the southeastern coast of Westeros overlooking Shipbreaker Bay.

History
Storm's End's construction was attributed to Durran, a legendary figure of the Age of Heroes, who earned the hatred of the sea god and the wind goddess when he took Elenei, daughter of the two gods, as his wife. In rage, the two gods sent massive storms to destroy Durran's keep. Durran defied the gods and built a larger and more formidable keep, but it was also destroyed. Durran's seventh keep, built allegedly with the aid of Bran the Builder, withstood the rage of Elenei's parents and gained the name of Storm's End.

Storm's End became the seat of the rulers of the Stormlands, the Storm Kings, for millennia. When Aegon the Conqueror invaded Westeros, he sent his commander and rumored half-brother, Orys Baratheon, to take Storm's End. The last of the Storm Kings, Argilac the Arrogant, left the safety of his stronghold and met Baratheon in open battle. Argilac was defeated, and Orys Baratheon took Argilac's domains, sigil, motto and daughter, becoming the founder of House Baratheon

One of the mightiest fortresses on the entire continent, Storm's End has endured many sieges but has never fallen to any attacker in its millennia-long history. Its seaward wall is 80 feet thick with a 150 feet drop into the sea below. The castle is said to be protected by spells woven into its walls that prevent magic from penetrating its defenses.

During Robert Baratheon's rebellion, Storm's End was besieged for over a year by the forces of House Tyrell, who had remained loyal to the Mad King, Aerys II Targaryen. The castle garrison, commanded by Robert's brother Stannis, was reduced to eating dogs and rats and were on the verge of resorting to cannibalism when they were saved by a shipload of onions, smuggled into the castle by the noted smuggler Davos. After Aerys' death, Eddard Stark bloodlessly raised the siege, as Lord Mace Tyrell realized that the war was lost, and he swore fealty to King Robert. Davos was raised to knighthood for his actions.

To Stannis's displeasure, he was made Lord of Dragonstone by his brother, leaving their infant brother Renly as the titular Lord of Storm's End. Stannis considered this a slight, as Dragonstone is even colder and harsher than Storm's End, despite Dragonstone being a fortress of great tactical importance and a history as a seat for Princes.

In the books
In the A Song of Ice and Fire novels, Storm's End consists of a massive curtain wall surrounding a single immense drum tower. Unlike many other castles, which consist of a complex of different buildings, Storm's End is entirely contained within one large building. This is due to the immense storms that frequently batter the castle.