The Different Types of Toilets in Later Castles

As you move into the later middle ages, you will see toilets in every room. You will find with later medieval castles that every room has a fireplace and window seat so you can sit an embroider or read in good natural light. These are aristocratic residences from the start and kings and bishops and earls and even lesser lords expect luxury in these buildings. Just hues on Instagram wanted to know who actually built these castles. I suppose I could expand that is how would you go about building a castle? Where would you start?