I sat in the sun on an upper deck (or whatever such a thing is called in a castle), against a wall to shelter from the blustery wind, and drew the top parts - chapel, armory, guard tower, all in full crenulation. Definitely not the sort of thing I get to draw back home.
Keeping an eye on the tide, I stopped in at the island's cafe for a "cream tea" - the traditional way in that part of the world to consume several thousand calories and not have it count as either lunch or dinner. There were two large creamy buttery scones, a bowl of clotted cream (basically a hybrid of butter and cream), a pot of jam, tea, and, of course, a jug of cream. It's the thing in Cornwall and neighbouring Devon. In Cornwall, one puts one's jam on the scone first, then the clotted cream. In Devon, one does the opposite. And so inter-regional scorn and contempt ensue. Being in Cornwall and a culturally-sensitive person, I went jam first. But I used a little artistic license in the drawing, because it looked better with the red on top.
To metabolize all that fat, I walked in the brisk wind through a nearby nature reserve before catching the double-decker back to Penzance. I walked around the old town, then, to balance my diet, stopped in at the Admiral Benbow for a pint. The old pub is where a distant relative set the first chapter of his Treasure Island, and it is full of paraphernalia, nautical and otherwise. It would drive a detail-oriented sketcher to drink (which is conveniently available).