The First Temple as drawn by Ezekiel had a winding staircase built within the thick wall which accessed the higher chambers. Josephus confirms that a large winding staircase existed in the First Temple. He claims it was built in its thick wall. The Bible states it was built in the thick southern wall. The Second Temple did not have a winding staircase.

"The door for the middle chamber was in the right side of the house and they went up with winding stairs into the middle chamber, and out of the middle into the third." MELAKHIM 6:8 JB

"The door for the middle chamber was in the right side of the house: and they went up with winding stairs into the middle chamber, and out of the middle into the third." 1 KINGS 6:8 KJV

There are clearly two winding staircases. In order to use two winding staircases you would need 3 chambers stacked on top of each other and such is the case in this model of Solomon's Temple when you incorporate Ezekiel's measurements. The winding staircase is attached to "the right side of the house" I Kings 6:8 and goes up through the arch in the ceiling.
At the North Gate the blood from the sacrifice was drained into a goblet which was brought up the stairs by the High Priest once a year. In the ritual it took blood to approach the throne room. Once the High Priest passed through the curtain and entered into the Holy Throne Room the blood was then sprinkled on God who was resting in the Ark. He was always pleased. There is no record of Him striking to death any High Priest who brought the blood.
The first set of winding stairs for house chamber (60 x 20) start there and connect up into the 40 x 20 chamber (I Kings 6:33) This winding stairway is linked by the word "goblet -door". The word "door" (Strong's 6907) The blood is robbed from the sacrifice and carried in a goblet through the doors of the winding staircase's to be placed as an offering on the Ark of the Covenant. This type of "goblet - door" is used only twice in the Bible I Kings 6:8 & 6:22. This "goblet door" links the winding staircase which appears to lead up to the Holy of Holies. The winding staircase of the lower chamber appears to enter into the Temple chamber of verse I Kings 6:22 . This unique "goblet-door" appears to link the winding staircase from the 60 x 20 House chamber up to the 40 x 20 Temple chamber.
In a horizontal Temple model the 60 x 20 chamber has a ceiling of 30, but the Holy of Holies has a ceiling of 20. If the Holy Chamber was elevated this would allow one winding staircase to enter it but where would the second winding staircase go? I Kings 6:2 & 8

Historian Josephus states this is how the winding staircases was constructed in Solomon's Temple.

"The king (Solomon) also had a fine contrivance for an ascent to the upper room over the temple, and that was by steps in the thickness of its wall."
Josephus, Antiquities of the Jews, B-VIII, C-3, V-2.

At the time that Josephus was told about the construction of Solomon's Temple it had been destroyed 500 years prior. So the memory of perhaps the Holy of Holies chamber being ascended by stairs might have been lost in the oral tradition, but if this model is correct it was sealed in the written tradition of the Hebrew Bible.
In the first winding staircase it incorporates one-fifth (1/5) of the thickness of the wall to stabilize the staircase. In the second chamber the winding staircase is constructed of and tied into one-forth (1/4) of the thickness of the wall. Probably because the walls are pylon shaped it uses less of the stone wall in the middle chamber. I Kings 6:31-33
Solomon's Temple is the only building on record which incorporated an arched ceiling which spanned 20 cubits (35'). Keep in mind this Temple predates the Roman Empire by nearly 1,000 years. Additionally there were three gigantic arches in Solomon's Temple for the 3 chambers of the main structure.

Question: Which type of temple could best utilize two winding staircases: A horizontal temple or a vertical Temple? The TWO winding staircases is more evidence that the main tower structure might have had three stories and built vertically.