Group 1 Alnwick Castle

http://www.kiddieholidays.co.uk/alnwick-castle-with-a-toddler/

https://en.wikipedia.org/wiki/Alnwick_Castle

Extra question: What famous movie was filmed in this beautiful castle?

Group 2 Schwerin Castle

https://en.wikipedia.org/wiki/Schwerin_Palace

Group 3 York Castle

https://en.wikipedia.org/wiki/York_Castle

Extra question: What is the name of the keep?

Group 4 Osaka Castle

https://en.wikipedia.org/wiki/Osaka_Castle

Group 5 Warwick Castle

https://en.wikipedia.org/wiki/Warwick_Castle + Warwick Castle Guide (Miss Dai)