O Castelo da Rocha Forte in Santiago de Compostela

You're standing at what's left of Rocha Forte, a medieval castle just outside Santiago de Compostela. There isn't much of it standing anymore, but take a good look around. This castle isn't perched on a hilltop, the way you'd expect a fortress to be. It sits down in a valley. That was a clever choice. The road from Padrón to Santiago ran right here, the pilgrim route coming up from Portugal. Anyone heading into town passed this spot, and from the castle you could keep an eye on all of that traffic.