Which preposition to use with bartizans

above Occurrences 1%

In Belsaye nothing stirred and none waked at this dead hour save where, high on the bartizan above the square and mighty keep, the watchman paced to and fro, while here and there from curtain wall and massy tower, spear-head and bascinet gleamed.

of Occurrences 1%

I well remembered the little inner room formed by the bartizan of the tower, and into this I tip-toed, feeling horribly guilty.

Which preposition to use with  bartizans