Ayodhya was the capital city of King Dasrath, It was the place where sage Vishwamitra had taken Shri Ram and Lakshman to save his"yagna".
Valmiki Ramayan 1/5,6, all chapters and other references, Shri Ram Charitmanas 1/15/1: 1/34/2,3: 1/189/1 to 1/207/4: 2/0/1 to 2/187/1 there are many references.
