From the air. From the ground they look like an irregular and haphazard series of corners, which is part of the point.

I visited Fort George in Scotland recently as I have family in the area and its interesting how little of the fort you can actually see from immediately in front of it - just the very top of the main walls - even though there are a lot of fortifications between those two areas.

You can see this in Google streetview if you go to the car park for visitor access - you can see almost nothing of the enormous fort even though it is only a couple of hundred metres away.