The curator Miguel Ángel Blanco wants us to think of paintings as objects. Presenting the backs of over 100 works, Blanco reveals their stories, secrets, and journeys with the hope of deepening our relationship with each piece. The idea for this exhibition began with a contemplation of Diego Velázquez’s Las Meninas, which shows a painter standing in front of a huge canvas, its ochre back facing the viewer. The show includes paintings from the Prado’s collection and borrowed works, some by artists who have never been exhibited at the museum, such as Vincent van Gogh and René Magritte. Organized into 10 sections based on themes rather than chronology or hierarchy, “On the Reverse” treats each piece “like an artifact in an archaeological excavation,” according to the Prado’s director, Miguel Falomir. —Jeanne Malle