Ephesus (Efes) is close to the town of Selcuk about an hours drive south of Izmir. Kusadasi is the nearest larger town, about 20km from Efes.
The Temple of Artemis at Ephesus was one of the seven wonders of the ancient world and was built around 550 BC, it was about four times the size of the Parthenon. Ephesus was part of the kingdom of Pergamum which Attalus III bequeathed to Rome in 133 BC. Ephesus was the most important Greek Roman city of proconsular Asia. Situated at the mouth of the Cayster River on a gulf of the Aegean sea, it flourished as an important commercial and export centre for Asia. By NT times it had grown to at least 250,000 people (Mounce). Gradually the harbour silted up and is now some miles from the sea. In modern day Turkey Ephesus is known as Efes. The Selçuk-Ephesus Museum is a must visit, many of the photos of statues are from the museum.
There is much information in the bible about the church at Ephesus. The church at Ephesus was founded by Paul where he reasoned with the Jews, he left Priscilla and Aquila there (Acts 18:19). Paul came back to Ephesus and found some disciples who had not received the Holy Spirit, they had only been baptised into John's baptism, when they were baptised in the name of the Lord Jesus the Holy Spirit came upon them (Acts 19:1-7). Paul spoke in the synagogue for three months (Acts 19:8) and then in the lecture hall of Tyrannus for 2 years (Acts 19:9-10). Then there was a disturbance because of the fertility goddess Artemis who brought the Ephesians wealth through making silver images of her (Acts 19:23), they were afraid that through Paul's preaching about Christ they would lose business. Paul left Timothy at Ephesus (1 Tim 1:3). He said good-bye to the elders of Ephesus at Miletus before going to Jerusalem (Acts 20:17-38) where he warned them that savage wolves will come in among them (Acts 20:29).
He also wrote to the Ephesians a long letter from which it is clear that they were a mature church. It is also thought that the apostle John and Mary, Jesus mother, settled at Ephesus. Some two-and-a-half centuries after Paul preached in Ephesus, the city hall was converted into a church and later used by the Council of Ephesus, which in 431 AD formally accepted the teaching that Jesus was both fully human and fully divine (C Hill, Prophecy Today, Vol. 11, No 5. p26-27.).