Philadelphia is the sixth of the seven churches addressed in Revelation. (The Letters to the Seven Churches, pg. 14).
“Philadelphia: A city of ancient Lydia in Asia Minor on the Cogamus River, 105 miles from Smyrna. It stood upon a terrace 650 ft. above the sea. Behind it are the volcanic cliffs to which the Turks have given the name of Devitt, or ‘inkwells’; on the other side of the city the land is exceedingly fertile, and there was produced a wine of whose excellence the celebrated Roman poet Virgil wrote. Philadelphia is not so ancient as many of the other cities of Asia Minor, for it was founded after 189 bc on one of the highways which led to the interior. … it sometimes bore the title of ‘Little Athens’ because of the magnificence of the temples and other public buildings which adorned it. Philadelphia quickly became an important and wealthy trade center, for as the coast cities declined, it grew in power, and retained its importance even until late Byzantine times.”
“Philadelphia,” International Standard Bible Encyclopedia.