Philadelphia appears to have been founded by Pergamum, perhaps at the time of their conquest of Lydia and Phrygia.
It was the gateway from the west into Phrygia; as such it was an important military point, and also a base for the spreading of Greek culture into Phrygia and Lydia.
The city was named in honor of the great love and loyalty between Eumenes II of Pergamum and Attalus II Philadelphus, his younger brother and successor.
After the earthquake of AD 17, the Caesar Tiberius canceled the city’s taxes for five years; Philadelphia took the name Neocaesarea in gratitude, and used that name for at least a couple decades.
This began a period of frequent earthquakes, which made it unsafe to be indoors. Strabo writes, “Philadelphia . . . has not even its walls secure, but they are daily shaken and split in some degree. The people continually pay attention to earth-tremors and plan their buildings with this factor in mind. . . . Different parts of the city are constantly suffering damage. That is why the actual town has few inhabitants, but the majority live as farmers in the countryside.”
During the reign of Vespasian, the father of Domitian, Philadelphia again took on another name: “Flavia,” in honor of the Flavian family to which Vespasian belonged. The reason is uncertain, but Vespasian was noted for his generosity to cities that suffered disasters.
The volcanic soil around Philadelphia was excellent for growing grapes, but not especially good for anything else; Strabo says nothing else grew there.
Though little is known about the synagogue in Philadelphia, it seems likely it was founded out of the large and prosperous Jewish community in Sardis.
The struggling church in its poor, half-ruined city is promised a secure place in the glorious, eternal city of God.