What is the importance of King's Landing in the novel, Fire & Blood?

King's Landing was nothing more than a small fishing village before the Targaryens arrived. It was the first place Aegon I set foot, and once he had conquered the realm, he decided to build a new city as the site of his throne rather than adopt one of the existing cities. It grows up without any real planning as people flock to the city by the thousand, but Jaehaerys spends much of his reign reconstructing the city. By the time he is done, it is the third largest in the realm.