Who was Andrew Wyeth's model for more than 200 paintings and drawings created between 1971 and 1985?

He met Helga when his elderly neighbor in Pennsylvania got sick and she was brought in to care for him.

But out of all of his models, Wyeth's relationship with Christina Olson was particularly special.  She is the central figure in his masterpiece, "Christina's World."

Upon his death, Wyeth made arrangements to be buried not far from Christina's grave in the Maine town of Cushing.