Where was first surah revealed?
Prior to the Caliph Uthman, the verses of the Koran were written
on "shards of pottery, scraps of hide, and the hearts of men (i.e.,
memorized)." The Koran is organized by length of passages, not in
chronological order, so no one knows which was the "first" surah,
although it's probably one of the short ones, toward the end of the
book.