Which Newbery Medal-winning book by E.L. Konigsburg features two children hiding in a museum?

The Newbery Medal-winning book by E. L. Konigsburg featuring two children hiding in a museum is From the Mixed-Up Files of Mrs. Basil E. Frankweiler.

Published in 1967, the novel follows Claudia and Jamie Kincaid, siblings who run away to New York City and secretly stay inside the Metropolitan Museum of Art. They hide from guards, sleep among museum furnishings, use fountain coins, and investigate a mysterious angel statue.

The novel won the 1968 Newbery Medal for excellence in American children's literature. Konigsburg achieved a rare double honor that year: her first published book, Jennifer, Hecate, Macbeth, William McKinley, and Me, Elizabeth, was also a Newbery runner-up.

A common mix-up is confusing the book with its film adaptations, including the 1973 movie starring Ingrid Bergman. The story's central museum is specifically New York's Metropolitan Museum of Art, commonly called the Met.