Acts 12:9,10

Acts 12:9-10. And he went out, and followed him.... When they were past the first and the second ward, they came unto the iron gate that leadeth unto the city. Silently, without a word, the radiant Messenger from heaven and the amazed apostle passed through the galleries of the fortress (the prison in which Peter was confined was most probably the tower of Antonia), past the first sleeping guard, then past the second, then through the great gates of iron which communicated with the city beyond, down a flight of seven steps, as one most ancient MS. (Codex D) tells us, into the street; and there the angel passed back into the unseen, leaving Peter alone, but free.