Philadelphia was located about twenty-eight miles southeast of Sardis. The city was founded in 189 BC by Attalus Philadelphus, for whom it was named. Some believe that it was so named also because of the love and loyalty existing between Philadelphus and his brother, the king of Lydia. The city was also known as Decapolis, because it was one of the ten cities of the plain.
It was sometimes called Little Athens because of the magnificence of its public buildings. Its modern Turkish name is Ala Shehr, which means "The City of God" or "The Exalted City." Philadelphia has thus been given a number of new names.
Philadelphia guarded and commanded an important pass through the mountains between the Hermus and Meander valleys. It was thus the keeper of the key to the door, or gateway, to the eastern highlands, with the power to open and close according to the will of the officials, Through this portal passed the mail and trade and commerce of the west to the wide regions of central and eastern Lydia.
Philadelphia was subject to frequent and severe earthquakes. Trench declared that "no city of Asia Minor suffered more, or so much, from violent and oft-recurring earthquakes," and the historian Strabo, who lived between 64 BC and AD 21, said that Philadelphia was "full of earthquakes." He may have been there at the time of the great earthquake that destroyed the city in AD 17. That was only one of a series of quakes that kept the citizens in a state of fearful expectancy. Strabo wrote: "Philadelphia has no trustworthy walls, but daily in one direction or another they keep tottering and falling apart. The inhabitants, however, pursue their original purpose, ever keeping in mind the writhing pangs of the ground, and building with a view to counteracting them."
Strabo was astonished that a city should ever have been founded in such a locality, and he questioned the sanity of the people for re-entering the ruined city and planning to rebuild to withstand the future shocks which were monetarily expected. He felt that when people are driven from a city by earthquakes they ought to be wise enough never to return. He declared that the walls of the houses were incessantly opening, and sometimes one, and sometimes another part of the city was experiencing some damage. The citizens therefore lived in constant dread of quaking earth and falling buildings.
Because of this situation the people often fled to the open country and lived in tents or booths in earthquake seasons in order to keep themselves beyond the range of disaster. Although the city was often shattered and the migrations from its ruins were frequent, so that its citizens lived in constant terror, yet in spite of an ever present sense of danger the brave Philadelphians were determined to make the city realize the aims for which it was founded. This constant fear of the day of trial , when the citizens must flee for their lives, made the language employed by Christ very striking. (Verses 10-12.) He encouraged His people with the promise that if faithful they would one day enter the New Jerusalem. the city of God, where they could dwell safely an "go no more out."
Philadelphia was a city of many new names. When the city was destroyed by the great earthquake of AD 17, Tiberious gave $600,000 to help rebuild. In appreciation the citizens changed the name of the city to Neo-Ceasarca in honor of the donor, but when the emperor became a cruel tyrant, the Philadelphians became ashamed of the new name. During the reign of Vespasian the Flavian family to rule. These changes of name doubtless called for great celebration of dedication, when the whole city worshipped the emperor in whose honor the new name was given.