It wouldt perhaps be easier, to monut a cornice high upon the wall. The
steel-wires or nylon-wires? are to be seen, but if you have to repaint
the holes a few times a year, your monument will became a swiss cheese.
If necessary you can provied this cornices with an alarm system,
impossible (nearly) if nailed.nailed.
Gerhard Dangel-Reese
Augustinermuseum Freiburg