“I am working so please do not disturb,” reads the block-lettered placard. “I do not sign autographs.”

This warning hangs on the door of an unassuming white clapboard house in Chadds Ford, Pa. It’s the house where Andrew Wyeth worked for nearly seven decades, producing many of the paintings that made him known as “America’s artist.” This summer, for the first time since his death in 2009 at 91, the studio is open for visitors.