I would like to know for sure, but I asume that you are allowed to stand on a tope without beating the guards first, since if you right click the tope you will see that it is not visited. The info gained about the size is not important.
@Red rush: Imo we should keep the rule. I noticed many games where it would decide the game if red rush was allowed.
Now that we discuss rules I think its time to change the rule where you should load the game if shackles is present and attacker cant catch the defender. Battle should finish and defender must fight.