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View looking east at the doorway that is on the west side of the cylindrical tower. Behind the student the solid interior cylinder is visible behind the modern supporting column.
There actually is an outer “cylinder” (the student is standing in it) that is constructed around a round central column and stairs are wedged in between the two parts. The round central column is visible behind and to the right of the woman in the picture. She is about 5 ft. 7 in. [1.5 m.] tall.
On this west side of the cylindrical tower (see lower right) it appears that the surface of the square base abuts up against it.