There are several small guard towers found throughout both Surface levels. Despite having guards armed with sniper rifles, none of them are placed on these towers. The reason why the towers aren't utilized has to do with how the game handles guards' line of sight and gunfire. Guards can only see Bond if they have a clear line of sight to him across collision tiles. Since the towers' collision tiles only connect to the ground's tiles at their ladders, the only place guards could actually see Bond is when he was standing in front of the ladder. Even if sight was faked, as the game does elsewhere, bullets work in the same way as line-of-sight and will be blocked by the collision tiles. Both of these limitations combined would have rendered any snipers on the towers completely ineffective. The towers were kept in the game merely for decoration and completeness.