Summerhall

King Daeron II Targaryen had Summerhall built in the Dornish Marches, right where that region borders the Reach and the Stormlands. In his early years as king he used it so often that the court all but moved there each summer; as he aged, he left King's Landing less and less.

The castle later passed to his youngest son, Prince Maekar, who kept his household there even after the Blackfyre Rebellion. It suited him: Daeron's heir, Baelor Breakspear, held Dragonstone, and the next in line, Aerys and Rhaegel, rarely strayed from court. Whoever held Summerhall came to be styled Prince of Summerhall, and Maester Melaquin served there.

After the tourney at Ashford Meadow, Maekar wanted his son Aegon brought back to the castle, but Ser Duncan the Tall took the boy on as his squire instead. Aegon kept a dragon's egg at Summerhall. Maekar himself went on living there after his brother, King Aerys I, named Brynden Rivers his Hand.

In 259 AC a fire tore through Summerhall and left it in the ruin it remains today. King Aegon V Targaryen died in the flames, along with his son and heir, Prince Duncan, the Lord Commander of the Kingsguard Duncan the Tall, and a good part of the court gathered there. That same day, in that same castle, Prince Rhaegar was born.

Rhaegar grew up with a strange attachment to those ruins: people said he was never happier than there, though the memory of what had happened also weighed on him. He liked to visit alone, and to sleep in the broken hall under open sky, by moon and starlight.

Maester Aemon came to believe that Rhaegar's birth, falling on the same day as the tragedy, marked him as the prince that was promised. Rhaegar, once grown, decided the prophecy pointed instead to his own son, Aegon.

With Robert's Rebellion underway, the lords of the Stormlands split between loyalty to King Aerys II Targaryen and loyalty to their own liege, Robert Baratheon. The king's supporters among Houses Fell, Cafferen, and Grandison agreed to gather their strength at Summerhall before marching together on Storm's End.

Robert learned of the plan in time and struck at Summerhall before they could join forces, defeating the three armies one after another. The ruins of the old summer castle gained one more chapter in their history, this time as a battlefield.