A gorgeous Gainsborough returns, street art goes AR and monuments are remade – the week in art

Back in the room … Thomas Gainsborough’s Blue Boy at the National Gallery in 1922. Photograph: © courtesy of the Huntington Library, Art Museum, and Botanical Gardens, San Marino, California

Exhibition of the week

Gainsborough’s Blue Boy
One of the most famous portraits ever painted in Britain returns from the US for the first time in a century.
• National Gallery, London, 25 January to 15 May