Ezekiel, priest and prophet, has been taken on a tour of the Temple in Jerusalem in the future. The tour continues in this chapter.
He was taken out of the inner portion of the Temple to the outer court and north. He sees a chamber. If I'm understanding there is a three story complex gallery that is between the inner and out courts. They opened to the north. Lots of details about this three story gallery—size and placement and such. There is a second three story block that's half the size of the first. This one has an entrance on the east side and you enter through the outer court.
Then he said to me, “The north chambers and the south chambers, which are opposite the separate area, they are the holy chambers where the priests who are near to the Lord shall eat the most holy things. There they shall lay the most holy things, the grain offering, the sin offering and the guilt offering; for the place is holy. Ezekiel 42:13
So, as Ezekiel understood it, there would still be a priest class and sacrifices. These priests are to enter from a different door and put on special garments just for this purpose.
He left there and went to the east side.
He measured it on the four sides; it had a wall all around, the length five hundred and the width five hundred, to divide between the holy and the profane. Ezekiel 42:20
All four sides measured the same, 500 reeds. Ryrie estimates this at about a mile on each side!
I don't understand the final note that the measurements divide between the holy and profane.