Laodicea
A city which was located in the Lycus Valley in the province of Phrygia. It was also situated on an ancient highway that ran from Ephesus to Syria. This city was located 10 miles west of Collosae and six miles south of Hieropolis and was mainly known for four reasons: 1. for hosting one of the seven Asia Minor churches, 2. It was a somewhat revered and wealthy city in Roman times and culture, 3. its medical school concocted a popular eye salve, and 4. It's manufacturing of black-wool garments.
It was founded by the Seleucids in 3rd Century B.C. and named after Laodice, who was the wife (and sister) of Antiochus II. It was destroyed by an earthquake in A.D. 60 but the citizens were so wealthy they refused reparations for the earthquake from Rome and rebuild it themselves.
At the time of writing the Epistle to the Colossians, It is unlikely that Paul had been to Laodicea. The Church at Laodicea was likely founded by Epaphras (perhaps alongside others). There is a letter "addressed" to the Laodiceans that Paul refers to in Col 4:16 (Compare with Notes on Colossians 4:16).
It lacked a sufficient and permanent supply of water, so water was brought in from five miles away in modern day Denizli. The water pipes were three foot across, cemented together. By the time the water reached Laodicea, it was lukewarm and tasted horrible.
Jesus also uses imagery about this water in comparison to their relationship with Him. He said they were neither Hot nor Cold so He would "spew" them out of His mouth. This imagery is speaking to the fact that they were lukewarm for Christ. They were spiritually amateur and not growing in obedience or "works". They were unlike Colossae's cold refreshing water or the Hot Springs at Hieropolis.
In Revelation 3:17, Jesus ascribes to them a self-sufficient attitude which aligns with their previous attitude of the rebuilding from the earthquake in A.D. 60. Jesus ascribes this attitude by saying "For you say, I am rich, I have prospered, and I need nothing, not realizing that you are wretched, pitiable, poor, blind, and naked." It is no coincidence that Jesus points out these three attributes seeing as they were wealthy, eye doctors, and an exporter of their black-wool clothes. Jesus is saying that their physical things that are perishable are worthless in the eyes of God. He says that regardless of the fact that they say they are rich, prosperous, lacking in nothing, etc, that they should "buy from me gold refined by fire, so that you may be rich, and white garments so that you may clothe yourself and the shame of your nakedness may not be seen, and salve to anoint your eyes, so that you may see". Although they had riches, they were not imperishable. Although they had clothing, they had no white garments of Christ. Although they had physical eye salve, they had not spiritual eyesalve.