Summerhall

Summerhall was the old summer palace of House Targaryen, built by King Daeron II to the south of King's Landing, in the Stormlands but near the borders of the Reach and Dorne. It was the third and newest of House Targaryen's strongholds, after Dragonstone and the Red Keep of King's Landing.

Summerhall was destroyed by fire approximatley forty years before the events of the series begin.

Robert Baratheon killed his first man in anger in a battle near Summerhall, a knight of House Tarly, during Robert's Rebellion.

In the books
In the Song of Ice and Fire novels, Summerhall has special significance for several members of House Targaryen. King Daeron II built it as a place of peace and relaxation away from court. One of his sons, Prince Maekar, adopted it as his main household. According to rumour, the fire that destroyed the castle was the result of an attempt to hatch dragon eggs which went badly wrong. King Aegon V, his heir Prince Duncan the Small and many members of his household were killed during the fire, which resulted in King Jaehaerys II taking the Iron Throne. However, the fire was said to have traumatised King Jaehaerys, and he died young only two years later, leaving his son Aerys II Targaryen as King.

Aerys II's own son, Prince Rhaegar Targaryen, was fascinated by the ruins of Summerhall and visited there several times.