Pausanius 1.3.5: Pausanius refers to the sanctuary of the Mother of the Gods. Encyclopedia Britannica confirms this is Cybele, but she is sometimes identified as Rhea. Pausanius refers to her once again in 7.20.3. Due to her affiliation in this paragraph with Attis, and through confirmation of outside sources, I can confidently say that this is all correct history. With the exception of Pheidias being the one who built it. https://www.britannica.com/topic/Great-Mother-of-the-Gods