John Bunyan was a 17th century English preacher who spent twelve years in prison for his Christian faith and wrote over 40 books. His best known writing is Pilgrim's Progress, one of the most famous and popular books in all of world history.
John Bunyan wrote the following account when he was a young man, of how an angel was sent by the Lord to take him to see heaven and hell. It is a true story, not an allegory or fictional book. While all visions must be judged by the Bible, these seem very scriptural and were used by the Lord to help transform young John into a mighty man of God.