Green Knowe is a fictional house featured in the children's book series by Lucy M. Boston. It is set in the English countryside and is known for its beautiful gardens and rich history. The house is depicted as a magical place where the past and present intertwine, allowing characters to experience the lives of those who once lived there. The stories revolve around a young boy named Tolly who visits his great-grandmother, Granny, at Green Knowe. Throughout the series, Tolly encounters various spirits and adventures, highlighting themes of friendship, family, and the importance of nature. The enchanting atmosphere of Green Knowe captivates readers and invites them into a world of imagination.