John Gill Commentary Nehemiah 2:13

"And I went out by night by the valley gate, even toward the jackal`s well, and to the dung gate, and viewed the walls of Jerusalem, which were broken down, and the gates thereof were consumed with fire." — Nehemiah 2:13 (ASV)

And I went out by night, by the gate of the valley
Where that formerly stood, for the gates had been burnt, and were not as yet rebuilt; this was the gate that led to the valley of Jehoshaphat, according to some; or rather to the valley of dead bodies, through which the brook Kidron ran, see (2 Chronicles 26:9) (Jeremiah 31:4) it is the gate through which Christ went to Calvary; it led to Shiloh, Bethhoron, and Golan:

even before the dragon well ;
so called from its winding about, just as a crooked winding river is called serpentine; though some think here stood an image of a dragon, either in wood, or stone, or brass, out of the mouth of which the water flowed from the well; and others, that since the desolations of Jerusalem, serpents or dragons had their abode here:

and to the dung port ;
by which they used to carry the dung out of the city, and by which they went to Joppa, the sea, and all the western parts:

and viewed the walls of Jerusalem :
in what condition they were, what was necessary to be wholly taken down, and where to begin to build: it must have been a moonlight night or he could not have taken a view; for to have carried torches or lamps with them would have discovered them:

and the gates thereof were consumed with fire ;
nothing of them remained.