Six onion-roof towers supporting heavens

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So it gets interesting when you also take into account the other meaning of "ciborium", which is "(2) A canopy resting on columns over the altar."

Coincidentally (or not) supported by 6 columns in the church of the Holy Sepulchre (You are not allowed to view links. Register or Login to view., f. 51v, ca. 1469/70):

   

Many towers with onion or bulb-shaped roofs in Jerusalem:

   
Map of Jerusalem, last quarter of the 15th century: You are not allowed to view links. Register or Login to view.