During this second journey Paul was inspired to take the gospel to Europe for the first time. This second missionary journey ended forty months later with Paul's arrival at Jerusalem during the fall festival season in 52 A.D. This journey is covered from close to the end of Acts 15 to Acts 18:21 - 22.
During this second journey Paul revisited the ekklesia (groups of converted people or churches) at the following locations.
From Antioch, Pisidia, Paul traveled to Europe and planted ekklesia (churches) in the following cities.
Three years after establishing the church Paul wrote an epistle to the Corinthians that we now refer to as 1 Corinthians. This was, however, not the first epistle Paul had sent to them. We know there was at least one previous epistle because of Paul's comments in 1Corinthians 5:9.
This letter, apparently a relatively short one, was written to address the corrupting influence that the Corinthian believers were being exposed to by permitting a fornicator to assemble with the church (see 1Corinthians 5). The fornicator was apparently a young man who was cohabiting with his father's wife (his stepmother).
Paul visited Ephesus for a short time on the return leg of his second missionary journey, planting a fellowship at Ephesus and leaving Aquila and Priscilla in the city to serve the brethren there (Acts 18:19). Some of these brethren may have been believers since Pentecost of 30 A.D.
18 Paul stayed on with the believers in Corinth for many days, then left them and sailed off with Priscilla and Aquila for Syria . . . 19 They arrived in Ephesus, where Paul left Priscilla and Aquila. (Acts 18).