Pergamos was one of the churches of the Apocalypse, located in a great, historic city of that name. It was beautiful, but the Bible says it was a city where satan's seat was located.
Revelation 2:12-13, And to the angel of the church in Pergamos write; These things saith He which hath the sharp sword with two edges;
I know thy works, and where thou dwellest, even where Satan's seat is: and thou holdest fast My name, and hast not denied My faith, even in those days wherein Antipas was My faithful martyr, who was slain among you, where Satan dwelleth.