Every kid has a clear idea of what a castle is. All you have to do is go to the beach and you see sand castles with moats and crenelations.
We generally don’t think of great lords living in towers. Walking in France and Spain I got to see a number of towers like this at Ruesta in Spain. This castle (really a couple of towers) from the 11th century guarded the frontier between Navarre and Aragon and doesn’t look much like the castles of our imagination.
We think of castles generally as looking like this Templar Castle in Pontferrada
The documents specify some medieval lords, like my medieval lady, Ermengarde, Viscountess of Narbonne, lived in palaces. Bishops always had palaces, but what were the palaces of the great nobles like? Unfortunately, there are few examples left of twelfth-century, non-religious architecture.
I did see and go into a medieval palace in Estella, Spain, the palace of the kings of Navarre. Here’s what it looks like.
It looks much more livable than the two “castles” above it. It was a McMansion of the middle ages.