We walked through the castle and the various exhibits, which told not only of Robin Hood, King John, and Richard the Lionheart, but also of the many years of history in Nottingham much before and after that time. It was really comprehensive, and I learned a lot more than I thought I would. We also took the guided tour of the caves under the castle, which was really awesome because the guide told us stories throughout history of the caves and the various uses - some quite scandalous ones involving the monarchs!
We finished the day by eating at Ye Olde Trip to Jerusalem, which is a pub that was once an inn, and is the oldest one in England. Richard the Lionheart and his men stayed and ate there right before leaving on the 3rd Crusade! It's built into the sides of the caves, so the inside has different levels and some of the walls and ceilings are solid rock. My cousin and I had the Robin Hood Ale, which was delicious, and some really great food! I was stuffed for hours.
We paid really minimally and got so much out of it.
Not to mention, it was really fun!
Nottingham - well worth it.