The Cloisters museum may seem fantastical, but it’s a real place overlooking the Hudson River in New York City. It began with the private collection of the American sculptor George Grey Barnard in the early 20th century. In 1925, it was bought by the Metropolitan Museum, financed by John D. Rockefeller Jr., and updated. Rockefeller hired the architect Charles Collens, who had prior experience designing gothic-style churches, to create the new space. It officially opened in 1938. The Cloisters museum is now a blend of original medieval elements, sourced primarily from France, and new, reconstructionist architecture. It’s famous for its broad collection of medieval art and artifacts, including tapestries, stained glass, and illuminated manuscripts.

There are three gardens within the Cloisters, though the novel simplifies and condenses them. The gardens contain many rare plant specimens intended to convey a garden in medieval times. Many of them reflect the plants depicted in the museum’s artwork. Unlike in the novel, the Cloisters gardens are managed by a team of trained horticulturalists; the senior members are historians with a background in period-appropriate gardening techniques.