Since its closure in mid-March, the halls are eerily quiet at Madrid's Reina Sofia. The museum used to be crowded with art lovers and students who come to explore masterpieces by the 20th century's most prominent artists like Picasso and Magritte. "The museum misses happiness," said Mari Carmen Pinedo Cazorla, a security guard at the museum. In Madrid's Reina Sofia, the most visited museum in Spain, experts have always been ...