One of the most classical elements of ancient greek and roman architecture, the was used first at the temple complexes of mentuhotep andhatshepsut, establishing an architectural language that continues still today.

The word filling the blank space is:
"Column" 

These were Greeks who actually developed the classical orders of architecture, these are easily recognizable by the columns and its various elements.

A column is a pillar usually in a round shape which is used as compression member in architecture. 

the answer would be (b). the stave church in borgund, norway is an example of norse architecture.