After Nemrut put boys to the sword and killed them, Prophet Abraham's mother secretly gave him birth in a cave. He was raised partially by his mother and by gazelles. Prophet Abraham, who later brought monotheism and had Kaaba built, had fought the cruel leader Nemrut and the idolatrous. He called the people to believe in only one God by tearing idols apart. Reacting towards this rebellion, Nemrut wanted to burn Prophet Abraham in a huge pile of woods. As soon as Prophet Abraham is put through the fire; the fire turns into a clear pool. The burning woods turn into fish. Ever since, it is called as Göle Halil-iü Rahman River. The lake next to it, Ayn-Zeliha is made up of the tears of Zeliha, Nemrut's foster daughter. After defeating Nemrut, Prophet Abraham settles at Harran with his father Tareh (Azer) and his nephew.

At Kalirrhoe or Güzelpınar as we call it today, the abundant and fruitful water boiling at the fall of the castle, has been perceived as holy water throughout the history.  A place, stirring peace and tranquillity thanks to the religious structures around it, the Pool of Abraham and the fish living inside it are considered sacred. Nobody touches the fish and feeding them is accepted as doing a good deed.

Under the shadow of plane trees and decorating the riverside, Rızvaniye Mosque is an Ottoman piece. Halil İbrahim Mosque located in the southeast of the lake, is an Ayyubid piece.  Right next to this mosque, there is a dervish convent covering the Church of Mary where Mandylion, the cloth upon which a miraculous image of the face of Jesus had been imprinted.

Makam-ı İbrahim, storied as the cave where Prophet Abraham was born, and Makam-ı İbrahim Mosque are located at the southeast of the park. It is believed to be the place where Prophet Abraham was born and breastfed by gazelles. This place used to be a church, too.

Looking down on the city, the most outstanding character of the castle over the lake is the two huge pillars with Korinth capitals. In people's belief, these pillars are those of catapult built by Nemrut. According to the Syrian inscription written on the pillars, this monument was raised in honour of Shalmat, the wife of the Great Abgar also known as the King of Abgar (172-212).

Only a small part of the castle dating back to BC 3th century or even older times, can be observed. It is still one of the most beautiful sight-see locations of Urfa.