Revelation 2:1 To the angel of the church of Ephesus write, ‘These things says He who holds the seven stars in His right hand, and who walks in the midst of the seven golden lampstands:
The church of Ephesus is the only church that had an epistle written to them that was canonically accepted into the Bible. Though dates can be (and will be) speculative as to precisely when each epistle was written, it is generally believed that the letter to the Ephesians was written around 60 AD.