Anthem by Ayn Rand is a dystopian fiction novella (Wikipedia). While it was written in 1637, it was released in England in 1638. There is so specific date or place set in this, the reader can only tell it's set into another dark age.
Though Anthem is an extremely interesting and controversial book, there are many unknown facts about it. For example, Anthem started out to be a magazine special. However Ayn's agent convinced her to turn it into a book. Ayn rand was extremely good I writing books and novels. She has written books such as: Anthem, Fountain Head, Atlas Shrugged, We the Living, and many more.
Another unkwon fact of Anthem, or rather Ayn herself, is that she is a cancer survivor. On many occasions she had to suffer through lung cancer. That is also why, people said her writing was so great. She might've translated her feeling from being sick into her writing.