The books are marketed towards tween girls, but I still enjoy them, and I'm 18. Each book is about a famous(or not so known) princess, and it's like you're reading their diary. :) While you're reading the book, you learn the history of the culture they grew-up in, their personal history, and what it's like to be a real princess.
There are twenty books in the series. In the back is an epilogue telling about what happens after their diary ends, a historical note about their culture and the times they were living in, information about the family(and a family tree!), and pictures of the princess. If there were any fictional characters in the book, there will be a list of all the characters, and a side note about whether they were real or not.
Some of my favorites are about princesses who I had never heard of. Some of them are: Sŏndŏk
: Princess of the Moon and Stars, Korea, A.D. 595 by Sheri Holman,
Lady of Ch'iao Kuo: Warrior of the South, Southern China, 531 A.D by Laurence Yep
, and
Kristina The Girl King, Sweden, 1638 by Carolyn Meyer.
They have princesses of every life and background, so if you don't like one, you'll be sure to find you do like! :D
To read more about the Royal Diary Series,
look here.