The Enchanted Castle BY E. NESBIT

The enchanted castle of the title is a country estate in the West Country seen through the eyes of three children, Gerald, James and Kathleen, who discover it while exploring during the school holidays. The lake, groves and marble statues, with white towers and turrets in the distance, make a fairy-tale setting, and then in the middle of the maze in the rose garden they find a sleeping fairy-tale princess.

WIKI