Still on the New Testament letters, this video is about the literary context – how people of that time wrote their letters.
These videos are produced by a group called BibleProject; their website is at https://bibleproject.com/ with lots more information
It is interesting to find out more about the people Paul mentions in his letters, and I found a Wikipedia page which summarises them and links to individual pages for almost all of them. (Although referring to a couple of people who would later lead the church in Rome as ‘Pope’ is seriously anachronistic!)
Dip in to it and have a read about some of these people.