The description of Jacob's ladder appears in the Book of Genesis(28:11-19):
Jacob left Beersheba, and went toward Haran. He came to the place and stayed there
that night, because the sun had set.
Taking one of the stones of the place, he put it under his head
and lay down in that place to sleep. And he dreamed that there was a ladder set
up on the earth, and the top of it reached to heaven; and behold, the angels of God were ascending
and descending on it!