Paul wrote Ephesians around A.D. 64 while he was in prison in Rome. It was carried to Ephesus by Tychicus, who also carried Paul’s letters to Colossi and Philemon.
Ephesus was the queen city of Asia Minor, situated about three miles from the Aegean Sea on the Cayster River, and had a population of about 340,000. It was the capital of the proconsular province of Asia and was one of the most important cities visited by the Apostle Paul. Ephesus was noted for the Great Temple of Diana (Artemis), and open-air theater seating 25,000, a magnificent stadium, and the shrine of Serapis (an Egyptian divinity). Ephesus was famous for its rich culture: Oriental religion, Greek philosophy, Roman government and worldwide commerce.
At the close of his second missionary journey, Paul made a brief visit to Ephesus, left Priscilla and Aquila there to work in his absence, and promised to return (Acts 18:19-21). Apollos spent some time there (Acts 18:24-28). On his third missionary journey, Paul remained in Ephesus for about three years evangelizing the city and the surrounding region. On his last voyage to Jerusalem, Paul met the elders of Ephesus at Miletus (Acts 20:17-38). — King James Bible Commentary, page 1560.
The oldest and most reliable Greek manuscripts do not have the words “which are at Ephesus.” However, the great majority of Greek manuscripts do include the words “in Ephesus,” and there are no Greek manuscripts which include the name of any other city. In Colossians 4:16, Paul mentions “the epistle from Laodicea.” Perhaps the autograph copy had a blank space in Ephesians 1:1, and since most of the manuscripts were copies of the letter sent to Ephesus, it came to be known as the Epistle to the Ephesians. No doubt it was a general or circular letter for the churches of Asia Minor. The letter lacks a personal tone; there are no personal greetings and no personal references. — King James Bible Commentary, page 1560.
It’s great subject is “the mystery” referred to in Romans 16:25. It had been kept secret since the world began; not made known to the sons of men (Ephesians 3:5); hidden in God (Ephesians 3:9); never revealed in the Scriptures but communicated to the apostle by Christ Himself (Ephesians 3:3). This great mystery, i.e., “secret” is that of the “new man” (Ephesians 2:15), above all heavens, “the one body” of which Christ is the Head, and an election taken out of the earth and separated from it, the members. This “new man” must not be confounded with the earthly kingdom which is to be composed of all people, as foretold in the Scriptures (Genesis 12:3; Romans 15:8-12) in union with and under the head-ship of Israel. — Williams, page 919
The resources I am using for this study are:
In the Heavenlies: Practical Expository Addresses on the Epistle to the Ephesians, by H.A. Ironside. (1937) Loizeaux Brothers, Publishers, New York, New York
Paul’s Epistle to the Ephesians, by Paul M. Sadler (1999) Berean Bible Society, Germantown, Wisconsin
Ephesians and Colossians in the Greek New Testament, by Kenneth S. Wuest (1953) Wm. B. Eerdmans Publishing Company, Grand Rapids, Michigan
Complete Bible Commentary, by George Williams
King James Bible Commentary (1983) Thomas Nelson, Nashville, Tennessee