Edinburgh Castle. What a mighty sight. The Royal Mile begins at the top of the rock where the castle sits, and goes all the way down to the Holyrood Palace, where the royal family stays while in town.
I didn’t actually visit the castle during this trip because I have gone all through it before, years ago, and I wanted to get up to Calton Hill. I had four hours to walk up there, and back down, along with catching a bite before the coach showed up to take us back to the hotel. I did have the option of catching a bus or taxi back, but I was up for the challenge.
Give yourself at least 2-4 hours to walk through the castle when you visit. There is so much to see! I would also suggest renting the ear-phones from the entrance area, if you do not have someone to walk you around and explain everything.