On a recent foray into Wales, I paused to explore Raglan Castle.
“Notice,” said the guide book sternly as I passed the gatehouse, “the machiolations”.
Fortunately, it went on to explain that a machiolation is “an arched opening at battlement level, through which suitable missiles could be dropped on a besieging army”. If you wish to notice them, you can do so on the top of the gatehouse towers over on the right hand side of the picture above.
Honestly, machiolations aside, it's a really good castle and well worth a visit. It's a fabulous mix of different historical layers as subsequent owners changed it from a medieval defence into a fancy status symbol with pleasure gardens, then had to bring it hastily up to snuff for the Civil War. Sadly it turned out to be on the wrong side of that particular conflict, and the keep was deliberately undermined to collapse into the moat when the Right But Repulsive side won.