I mean, there are plenty of ruins in Phrygia--but I suspect naturally that you mean ruins left by the Indo-European Phrygian people. There are plenty, both from the period when an independent Phrygian state existed and from after their absorption into first the Lydian state and then subsequent states. The most famous site is Gordium, which was first excavated in 1900--the tumuli there are particularly famous. Also famous are the ruins of Pessinus, a city founded probably after the end of the Phrygian state (though tradition held that it was pre-classical--the existing site, though, is not). Pessinus is famous for its extensive temple complexes, including the great sanctuary to Cybele. Smaller sites exist throughout Phrygia, and we shouldn't think of sites post-dating the end of the independent Phrygian state as being somehow foreign--the Phrygians were highly successful at maintaining the independence of their cultural identity throughout the classical period up until late antiquity