Hi Tina! History was an excellent guess. The more ancient the better.
There are so many things to like about the HP books, but something I really enjoyed was how J.K. Rowling weaved her back stories. Everything had meaning. Example: Hagrid brought baby Harry to the Dursley's on a flying motorcycle. Neat right? But wasn't it even better when we learned some books later that it belonged to Sirius? In the first book, Harry speaks to the snake at the zoo. Wasn't it cool to look back on that and say, "oh yeah!" when you read CoS? There are way too many more examples to name, but I love how well J.K. Rowling did that.
I kinda guessed history, cuz you said you had a degree in Archaeology!! That's what I love about Jo's writing too! Shed odesn't leave holes in between!! So what's your fave potion and why? Mine is Polyjuice potion! And what's your fave book?

Tina.