From the Mixed-Up Files of Mrs. Basil E. Frankweiler

From the Mixed-Up Files of Mrs. Basil E. Frankweiler is the story of two siblings, Claudia and Jamie, who run away from home when Claudia feels unappreciated. They take up residence in the Metropolitan Museum of Art in New York City, bathing in its fountain and using the tossed coins to supplement Jamie’s savings. 

Eventually the character of Mrs. Basil E. Frankweiler appears. She is a high-level art collector who sold a particularly intriguing sculpture to the museum. Is it a Michelangelo? The children use the last of their cash to visit Frankweiler in her home with the hopes of learning who created the art. A wealthy and generous woman, ultimately she helps them return home. 

This novel took the Newbery Medal in 1968, and the story is still engaging for upper elementary readers. Its Lexile score is 700L.